Nitrogenated heterocyclic compound

ABSTRACT

The present invention provides a compound having a PDE2A selective inhibitory action, which is useful as an agent for the prophylaxis or treatment of schizophrenia, Alzheimer&#39;s disease and the like. 
     The present invention is a compound represented by the formula (1): 
                         
wherein each symbol is as described in the specification, or a salt thereof.

TECHNICAL FIELD

The present invention relates to a nitrogen-containing heterocycliccompound having a PDE2A selective inhibitory action, which is useful asan agent for the prophylaxis or treatment of schizophrenia, Alzheimer'sdisease and the like.

BACKGROUND OF THE INVENTION

Cyclic nucleotide phosphodiesterases (PDEs) are enzymes that regulatethe cellular levels of the second messengers, cyclic adenosinemonophosphate (cAMP) and cyclic guanosine monophosphate (cGMP), bycontrolling their rates of degradation. PDEs are a superfamily ofenzymes encoded by 21 genes and subdivided into 11 distinct familiesaccording to structural and functional properties. The PDE enzymesselectively catalyze the hydrolysis of the 3′-ester bond of cAMP and/orcGMP, forming the inactive 5′-monophosphate. On the basis of substratespecificity, the PDE families can be further classified into threegroups: i) the cAMP-PDEs (PDE4, PDE7 and PDE8), ii) the cGMP-PDEs (PDE5,PDE6 and PDE9), and iii) the dual-substrate PDEs (PDE1, PDE2, PDE3,PDE10 and PDE11).

cAMP and cGMP are involved in the regulation of virtually everyphysiological process such as pro-inflammatory mediator production andaction, ion channel function, muscle relaxation, learning and memoryformation, differentiation, apoptosis, lipogenesis, glycogenolysis andgluconeogenesis. Especially, in neurons, these second messengers have animportant role in the regulation of synaptic transmission as well as inneuronal differentiation and survival (Non-Patent Document 1).Regulation of these processes by cAMP and cGMP are accompanied byactivation of protein kinase A (PKA) and protein kinase G (PKG), whichin turn phosphorylate a variety of substrates, including transcriptionfactors, ion channels and receptors that regulate a variety ofphysiological processes. Intracellular cAMP and cGMP concentrations seemto be temporally, spatially, and functionally compartmentalized byregulation of adenylate and guanylate cyclases in response toextracellular signaling and their degradation by PDEs (Non-PatentDocument 2). PDEs provide the only means of degrading the cyclicnucleotides cAMP and cGMP in cells, thus PDEs play an essential role incyclic nucleotide signaling. Thereby, PDEs could be promising targetsfor various therapeutic drugs.

Phosphodiesterase 2A (PDE2A) is a dual substrate enzyme that hydrolyzesboth cAMP and cGMP. It is organized into four domains, N-terminus,GAF-A, GAF-B, and catalytic domains, and functions as a homodimer. PDE2Acatalytic activity is allosterically stimulated by cGMP binding. GAF-Bdomain binds with a high affinity and a high selectivity to cGMP. Aconformational change is caused by the cGMP binding in the PDE2Ahomodimer which causes an increase in the catalytic activity of theenzyme (Non-Patent Document 3-6). In contrast, there are as yet no knownin vivo examples that cAMP stimulates PDE2A catalytic activity, eventhough it can also bind to the GAF-B domain with a 30-100-fold loweraffinity than cGMP (Non-Patent Document 6 and 7). PDE2A activity maybecome functionally significant under conditions in which cellular cGMPconcentrations are elevated, which shows a physiological role for GAFdomain-regulation of the enzyme.

PDE2A is expressed in a wide variety of tissues and highly in the brain.The protein was originally purified from heart, liver, adrenal gland,platelets, endothelial cells, and macrophages (Non-Patent Document8-13). In the brain, the PDE2A mRNA levels are the highest in thecaudate lobe, nucleus accumbens, cortex (frontal, parietal and temporal)and the hippocampus, and are at least 10-fold lower expression in otherbrain regions (Non-Patent Document 14). This suggests that PDE2A maycontrol intraneuronal cAMP and cGMP levels in areas that are importantfor learning and memory formation.

Inhibition of PDE2A results in increased cAMP and cGMP levels that couldimprove cognitive function. In both cortical neurons and hippocampalslices, a PDE2A inhibitor potently increased cGMP concentrations in thepresence of guanylate cyclase activators and also increased cAMPconcentrations in the presence of forskolin (Non-Patent Document 15).The PDE2A inhibitor was also found to potently increase the induction oflong-term potentiation (LTP) in hippocampal slices in response to a weaktetanizing stimulus. This effect on LTP in slices suggests that PDE2Ainhibition has positive effects on learning and memory in vivo(Non-Patent Document 15). In fact, the same PDE2A inhibitor increasedretention on both novel object and social recognition tasks in rats, andimproved object memory and object recognition task in 3-, 12-, and24-month old rats. It also attenuated the extradimensional (ED) shiftdeficit on extradimensional-intradimensional (ED/ID) cognitive task insubchronic PCP-treated rats (Non-Patent Document 15-17). These resultssuggest that PDE2A inhibition could facilitate learning and memoryprocesses through potentiation of cAMP and cGMP-regulated signalingcascades.

Increased cGMP levels by PDE2A inhibition could also influence anxietyand stress-related events. PDE2A inhibitors decreased oxidative stressand induced the expression of NADPH oxidase subunits in oxidative stressinducer-treated mice. It improved anxiety-like behavior in elevated plusmaze, open-field, and hole-board tests through the NADPH oxidase pathway(Non-Patent Document 18). In addition, PDE2A inhibitors also producedanxiolytic effects on behavior in non-stressed mice in the elevatedplus-maze and hole-board tests (Non-Patent Document 19). PDE2A may be anovel pharmacological target for treatment of not only cognitivedeficit, but also anxiety in neuropsychiatric and neurodegenerativedisorders.

These unique distribution and functions in the brain indicate that PDE2Arepresents an important novel target for the treatment ofneuropsychiatric and neurodegenerative disorders, in particularschizophrenia and Alzheimer's disease.

Patent Document 1 discloses, as a nitrogen-containing heterocycliccompound, a compound represented by the formula (I):

wherein

-   Z¹ and Z² are each independently N or CR (at least one is CR, and R    is halogen, —OH, —CN, fluoro-substituted C₁₋₂ alkyl, —O—(C₁₋₂)    fluoro-substituted alkyl, —S—C₁₋₂ fluoro-substituted alkyl or the    like);-   W is —O—, —NH—, —N(C₁₋₄ alkyl)-, —S—, —S(O)—, —S(O)₂— or the like;-   R⁶ is H, C₁₋₄ alkyl or fluoro-substituted C₁₋₄ alkyl, or two R⁶,    which are bonded to the single carbon atom, in combination    optionally form ═O;-   R¹ is carbocycle or heterocycle, each of which is optionally    substituted by halo, —CN, C₁₋₄ alkyl or the like;-   R² is carbocycle or heterocycle, each of which is optionally    substituted by halo, —CN, C₁₋₄ alkyl or the like;-   P is 1, 2 or 3;-   X² is C(═O), —C(═O)—O—*, —C(═O)—NH—*, —C(═O)—NHCR⁴R⁵—* or the like    (* means the binding position to R¹);-   R⁴ and R⁵ are each independently H, C₁₋₄ alkyl, —CF₃ or (C₁₋₃    alkyl)-CF₃,    which is a sirtuin modulator, and useful for treatment of    Alzheimer's disease, Parkinson's disease.

However, the structure of the present invention is different from thatof the above-mentioned compound.

DOCUMENT LIST Patent Document

-   Patent Document 1: WO 2011/059839

Non-Patent Document

-   Non-Patent Document 1: Nat. Rev. Drug Discov. 2006, vol. 5: 660-670-   Non-Patent Document 2: Circ. Res. 2007, vol. 100: 950-966-   Non-Patent Document 3: J. Biol. Chem. 1971, vol. 246: 3841-3846-   Non-Patent Document 4: J. Biol. Chem. 1973, vol. 248: 1334-1340-   Non-Patent Document 5: PNAS 2005, vol. 99: 13260-13265-   Non-Patent Document 6: British J. Pharmacol. 2010, vol. 161:    1645-1660-   Non-Patent Document 7: J. Biol. Chem. 2004, vol. 279: 37928-37938-   Non-Patent Document 8: J. Biol. Chem. 1982, vol. 257: 1973-1979-   Non-Patent Document 9: J. Biol. Chem. 1983, vol. 258: 12526-12533-   Non-Patent Document 10: Phosphodiesterase Inhibitors, Academic    Press: 21-40-   Non-Patent Document 11: Rev. Physiol. Biochem. Pharmacol. 1999, vol.    135: 67-104-   Non-Patent Document 12: Cell Signal 2004, vol. 16: 365-374-   Non-Patent Document 13: J. Histochem. Cytochem. 2009, vol. 57:    933-949-   Non-Patent Document 14: Neuropharmacology 2010, vol. 59: 367-374-   Non-Patent Document 15: Neuropharmacology 2004, vol. 47: 1081-1092-   Non-Patent Document 16: Mol. Neurobiol. 2010, vol. 41: 129-137-   Non-Patent Document 17: Neuropharmacology 2012, vol. 62: 1182-1190-   Non-Patent Document 18: J. Pharmacol. Exp. Ther. 2008, vol. 326:    369-379-   Non-Patent Document 19: J. Pharmacol. Exp. Ther. 2009, vol. 331:    690-699

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

The present invention aims to provide a compound having a PDE2Aselective inhibitory action, which is useful as a prophylactic ortherapeutic drug for schizophrenia, Alzheimer's disease and the like.

Means of Solving the Problems

The present inventors have conducted intensive studies, and have foundthat a compound represented by the formula (1) shown below unexpectedlyhas a superior PDE2A selective inhibitory action, and therefore, isuseful as a prophylactic or therapeutic drug for schizophrenia,Alzheimer's disease and the like, and completed the present inventionbased on these findings.

Accordingly, the present invention provides the following:

-   [1] A compound represented by the formula (1):

wherein

-   R¹ is a hydrogen atom or an optionally substituted C₁₋₆ alkyl group,-   R² and R³ are each independently a hydrogen atom or an optionally    substituted C₁₋₆ alkyl group, or R² and R³ in combination optionally    form, together with the adjacent carbon atom, an optionally    substituted ring,-   X is a bond or an optionally substituted C₁₋₆ alkylene group,-   A is an optionally substituted cyclic group,-   Z¹ is a group represented by CR^(Z1) wherein R^(Z1) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group or an optionally    substituted cyclic group, or a nitrogen atom,-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group or an optionally    substituted cyclic group, or a nitrogen atom,-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group, an optionally    substituted C₁₋₆ alkyl-carbonyl group or an optionally substituted    cyclic group, or a nitrogen atom, and B is a nitrogen-containing    aromatic heterocycle containing 1 or 2 nitrogen atoms, provided that-   2,3-dihydro-1-methyl-2-oxo-N-2-thiazolyl-6-[3-(trifluoromethyl)phenyl]-pyrido[2,3-b]pyrazine    -4(H)carboxamide,-   2,3-dihydro-1-methyl-N-(4-methyl-2-thiazolyl)-2-oxo-6-[3-(trifluoromethyl)phenyl]-pyrido[2,3-b]pyrazine-4(1H)carboxamide,-   2,3-dihydro-1-methyl-2-oxo-N-(tetrahydro-2-oxo-3-furanyl)-6-[3-(trifluoromethyl)phenyl]-pyrido    [2,3-b]pyrazine-4(1H)carboxamide,-   2,3-dihydro-    1-methyl-N-2-oxazolyl-2-oxo-6-[3-(trifluoromethyl)phenyl]-pyrido    [2,3-b]pyrazine-4(1H)carboxamide,-   2,3-dihydro- 1-methyl-2-oxo-N-    1H-1,2,4-triazol-3-yl-6-[3-(trifluoromethyl)phenyl]pyrido[2,3-b]pyrazine-4(1H)carboxamide,-   2,3-dihydro- 1-methyl-2-oxo-N-4-pyridinyl-6-[3    -(trifluoromethyl)phenyl]-pyrido [2,3 b]pyrazine-4(1H)carboxamide,-   2,3-dihydro-1-methyl-2-oxo-N-4-pyrimidinyl-6-[3-(trifluoromethyl)phenyl]-pyrido[2,3b]pyrazine    -4(1H)carboxamide,-   2,3-dihydro-    1-methyl-2-oxo-N-5-pyrimidinyl-6-[3-(trifluoromethyl)phenyl]-pyrido[2,3b]pyrazine    -4(1H)carboxamide,-   2,3-dihydro-    1-methyl-2-oxo-N-3-pyridazinyl-6-[3-(trifluoromethyl)phenyl]-pyrido[2,3-b]pyrazine-4(1H)carboxamide,-   2,3-dihydro-    1-methyl-N-[6-(4-morpholinyl)-2-pyridinyl]-2-oxo-6-[3-(trifluoromethyl)phenyl]-pyrido    [2,3-b]pyrazine-4(1H)carboxamide,-   N-(4,5-dimethyl-2-thiazolyl)-2,3-dihydro-1-methyl-2-oxo-6-[3-(trifluoromethyl)phenyl]-pyrido[2,3-b]pyrazine-4(1H)carboxamide,-   2,3-dihydro-    1-methyl-N-(5-methyl-2-thiazolyl)-2-oxo-6-[3-(trifluoromethyl)phenyl]-pyrido[2,3-b]pyrazine-4(1H)carboxamide,-   N-[5-[(dimethylamino)carbonyl]-4-methyl-thiazolyl]-2,3    -dihydro-1-methyl-2-oxo-6-[3-(trifluoromethyl)phenyl]-pyrido    [2,3-b]pyrazine-4(1H)carboxamide,-   N-(4,6-dimethyl-2-pyridinyl)-2,3-dihydro-    1-methyl-2-oxo-6-[3-(trifluoromethyl)phenyl]pyrido[2,3    -b]pyrazine-4(1H)carboxamide,-   2,3-dihydro-1-methyl-2-oxo-N-2-pyrazinyl-6-[3-(trifluoromethyl)phenyl]-pyrido[2,3-b]pyrazine-4(1H)carboxamide,-   2,3-dihydro-1-methyl-2-oxo-N-2-pyrimidinyl-6-[3-(trifluoromethyl)phenyl]-pyrido[2,3b]pyrazine-4(1H)carboxamide,-   N-[2-(1-azetidinyl)-4-pyridinyl]-2,3-dihydro-1-methyl-2-oxo-6-[3-(trifluoromethyl)phenyl]-pyrido[2,3-b]pyrazine-4(1H)carboxamide,-   2,3-dihydro-1-methyl-N-[6-(4-morpholinylmethyl)-2-pyridinyl]-2-oxo-6-[3-(trifluoromethyl)phenyl]-pyrido[2,3-b]pyrazine-4(1H)carboxamide,    and    N-[6-(1-azetidinyl)-2-pyridinyl]-2,3-dihydro-1-methyl-2-oxo-6-[3-(trifluoromethyl)phenyl]-pyrido[2,3-b]pyrazine-4(1H)carboxamide    are excluded, or a salt thereof (hereinafter to be referred as    compound (1)).-   [2] The compound or salt of the above-mentioned [1], wherein-   R^(Z1) is a hydrogen atom, a halogen atom, an optionally substituted    C₁₋₆ alkyl group, an optionally substituted C₂₋₆ alkenyl group, an    optionally substituted C₂₋₆ alkynyl group, an optionally substituted    C₁₋₆ alkoxy group, an optionally substituted amino group or a cyano    group, and-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group or an optionally    substituted cyclic group.-   [3] The compound or salt of the above-mentioned [1], wherein R^(l)    is a hydrogen atom.-   [4] The compound or salt of the above-mentioned [1], wherein R² and    R³ are both hydrogen atoms.-   [5] The compound or salt of the above-mentioned [1], wherein Z¹, Z²    and Z³ are respectively CR^(Z1), CR^(Z2) and CR^(Z3).-   [6] The compound or salt of the above-mentioned [5], wherein    R^(Z1)and R^(Z3) are both hydrogen atoms.-   [7] The compound or salt of the above-mentioned [5], wherein R^(Z2)    is an optionally substituted C₁₋₆ alkoxy group, an optionally    substituted C₁₋₆ alkyl group or an optionally substituted C₃₋₈    cycloalkyl group.-   [8] The compound or salt of the above-mentioned [1], wherein X is an    optionally substituted C₁₋₆ alkylene group.-   [9] The compound or salt of the above-mentioned [1], wherein A is an    optionally substituted phenyl group.-   [10] The compound or salt of the above-mentioned [1], wherein-   R^(l) is a hydrogen atom,-   R² and R³ are both hydrogen atoms,-   X is an optionally substituted C₁₋₆ alkylene group,-   A is an optionally substituted phenyl group,-   Z¹ is CH,-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is an optionally    substituted C₁₋₆ alkyl group, an optionally substituted C₁₋₆ alkoxy    group or an optionally substituted C₃₋₈ cycloalkyl group, and-   Z³ is CH.-   [11]    7-Methoxy-N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide    or a salt thereof.-   [12]    N-((1S)-1-(3-Fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide    or a salt thereof.-   [13] 7-Cyclopropyl-N-((1S)-2-hydroxy-2-methyl-1-(4-    (trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide    or a salt thereof-   [14]    7-Cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide    or a salt thereof.-   [15]    N-(1-(3-Fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide    or a salt thereof.-   [16] A medicament comprising the compound or salt of the    above-mentioned [1].-   [17] The medicament of the above-mentioned [16], which is a    phosphodiesterase 2A inhibitor.-   [18] The medicament of the above-mentioned [16], which is an agent    for the prophylaxis or treatment of schizophrenia.-   [19] A method of inhibiting phosphodiesterase 2A, which comprises    administering an effective amount of a compound represented by the    formula (1):

wherein

-   R¹ is a hydrogen atom or an optionally substituted C₁₋₆ alkyl group,-   R² and R³ are each independently a hydrogen atom or an optionally    substituted C₁₋₆ alkyl group, or R² and R³ in combination optionally    form, together with the adjacent carbon atom, an optionally    substituted ring,-   X is a bond or an optionally substituted C₁₋₆ alkylene group,-   A is an optionally substituted cyclic group,-   Z¹ is a group represented by CR^(Z1) wherein R^(Z1) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group or an optionally    substituted cyclic group, or a nitrogen atom,-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group or an optionally    substituted cyclic group, or a nitrogen atom,-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₈ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group, an optionally    substituted C₁₋₆ alkyl-carbonyl group or an optionally substituted    cyclic group, or a nitrogen atom, and-   B is a nitrogen-containing aromatic heterocycle containing 1 or 2    nitrogen atoms,-   or a salt thereof, to a mammal.-   [20] A method for the prophylaxis or treatment of schizophrenia,    which comprises administering an effective amount of a compound    represented by the formula (1):

wherein

-   R¹ is a hydrogen atom or an optionally substituted C₁₋₆ alkyl group,-   R² and R³ are each independently a hydrogen atom or an optionally    substituted C₁₋₆ alkyl group, or R² and R³ in combination optionally    form, together with the adjacent carbon atom, an optionally    substituted ring,-   X is a bond or an optionally substituted C₁₋₆ alkylene group,-   A is an optionally substituted cyclic group,-   Z¹ is a group represented by CR^(Z1) wherein R^(Z1) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group or an optionally    substituted cyclic group, or a nitrogen atom,-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group or an optionally    substituted cyclic group, or a nitrogen atom,-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group, an optionally    substituted C₁₋₆ alkyl-carbonyl group or an optionally substituted    cyclic group, or a nitrogen atom, and-   B is a nitrogen-containing aromatic heterocycle containing 1 or 2    nitrogen atoms,-   or a salt thereof, to a mammal.-   [21] Use of a compound represented by the formula (1):

wherein

-   R¹ is a hydrogen atom or an optionally substituted C₁₋₆ alkyl group,-   R² and R³ are each independently a hydrogen atom or an optionally    substituted C₁₋₆ alkyl group, or R² and R³ in combination optionally    form, together with the adjacent carbon atom, an optionally    substituted ring,-   X is a bond or an optionally substituted C₁₋₆ alkylene group,-   A is an optionally substituted cyclic group,-   Z¹ is a group represented by CR^(Z1) wherein R^(Z1) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group or an optionally    substituted cyclic group, or a nitrogen atom,-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group or an optionally    substituted cyclic group, or a nitrogen atom,-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group, an optionally    substituted C₁₋₆ alkyl-carbonyl group or an optionally substituted    cyclic group, or a nitrogen atom, and-   B is a nitrogen-containing aromatic heterocycle containing 1 or 2    nitrogen atoms,-   or a salt thereof, for the production of an agent for the    prophylaxis or treatment of schizophrenia.-   [22] A compound represented by the formula (1):

wherein

-   R¹ is a hydrogen atom or an optionally substituted C₁₋₆ alkyl group,-   R² and R³ are each independently a hydrogen atom or an optionally    substituted C₁₋₆ alkyl group, or R² and R³ in combination optionally    form, together with the adjacent carbon atom, an optionally    substituted ring,-   X is a bond or an optionally substituted C₁₋₆ alkylene group,-   A is an optionally substituted cyclic group,-   Z¹ is a group represented by CR^(Z1) wherein R^(Z1) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group or an optionally    substituted cyclic group, or a nitrogen atom,-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group or an optionally    substituted cyclic group, or a nitrogen atom,-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, an    optionally substituted amino group, a cyano group, an optionally    substituted C₁₋₆ alkyl-carbonyl group or an optionally substituted    cyclic group, or a nitrogen atom, and-   B is a nitrogen-containing aromatic heterocycle containing 1 or 2    nitrogen atoms,-   or a salt thereof, for use in the prophylaxis or treatment of    schizophrenia.

Effect of the Invention

According to the present invention, the compound having a PDE2Aselective inhibitory action, which is useful as an agent for theprophylaxis or treatment of schizophrenia, Alzheimer's disease and thelike, can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a graph that a test compound has an improvement effect forMK-801 induced disorder in Contextual fear conditioning test(Experimental Example 2).

DETAILED DESCRIPTION OF THE INVENTION

The present invention is explained in detail in the following.

The “halogen atom” in the present specification means, unless otherwisespecified, a fluorine atom, a chlorine atom, a bromine atom or an iodineatom.

The “optionally substituted hydrocarbon group” in the presentspecification means, unless otherwise specified, for example, an“optionally substituted C₁₋₁₀ alkyl”, an “optionally substituted C₂₋₁₀alkenyl”, an “optionally substituted C₂₋₁₀ alkynyl”, an “optionallysubstituted C₃₋₈ cycloalkyl”, an “optionally substituted C₃₋₈cycloalkenyl”, an “optionally substituted C₆₋₁₄ aryl”, an “optionallysubstituted C₇₋₁₄ aralkyl” or the like.

The “C₁₋₁₀ alkyl” in the present specification means, unless otherwisespecified, for example, methyl, ethyl, propyl, isopropyl, butyl,isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl,heptyl, octyl, nonyl, decyl or the like. The “C₁₋₆ alkyl” in the presentspecification means C₁₋₆ alkyl from among the above-mentioned “C₁₋₁₀alkyl”. The “C₁₋₅ alkyl” in the present specification means C₁₋₅ alkylfrom among the above-mentioned “C₁₋₁₀ alkyl”.

The “C₂₋₁₀ alkenyl” in the present specification means, unless otherwisespecified, for example, vinyl, propenyl, isopropenyl, 2-buten-1-yl,4-penten-1-yl, 5-hexen-1-yl or the like. The “C₂₋₆ alkenyl” in thepresent specification means C₂₋₆ alkenyl from among the above-mentioned“C₂₋₁₀ alkenyl”.

The “C₂₋₁₀ alkynyl” in the present specification means, unless otherwisespecified, for example, 2-butyn-1-yl, 4-pentyn-1-yl, 5-hexyn-1-yl or thelike. The “C₂₋₆ alkynyl” in the present specification means C₂₋₆ alkynylfrom among the above-mentioned “C₂₋₁₀ alkynyl”.

The “C₃₋₈ cycloalkyl” in the present specification means, unlessotherwise specified, for example, cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl, cyclooctyl or the like.

The “C₃₋₈ cycloalkenyl” in the present specification means, unlessotherwise specified, for example, cyclopropenyl (e.g.,2-cyclopropen-1-yl), cyclobutenyl(e.g., 2-cyclobuten-1-yl),cyclopentenyl (e.g., 1-cyclopenten-1-yl, 2-cyclopenten-1-yl,3-cyclopenten-1-yl), cyclohexenyl(e.g., 1-cyclohexen-1-yl,2-cyclohexen-1-yl, 3-cyclohexen-1-yl) or the like.

The “C₆₋₁₄ aryl” in the present specification means, unless otherwisespecified, for example, phenyl, 1-naphthyl, 2-naphthyl, 2-biphenylyl,3-biphenylyl, 4-biphenylyl, 2-anthryl or the like. The C₆₋₁₄ aryl may bepartially saturated, and examples of the partially saturated C₆₋₁₄ arylinclude tetrahydronaphthyl and the like.

The “C₇₋₁₄ aralkyl” in the present specification means, unless otherwisespecified, for example, benzyl, phenethyl, 1-methyl-2-phenylethyl,diphenylmethyl, 1-naphthylmethyl, 2-naphthylmethyl, 2,2-diphenylethyl,3-phenylpropyl, 4-phenylbutyl, 5-phenylpentyl, 2-biphenylylmethyl,3-biphenylylmethyl, 4-biphenylylmethyl or the like.

The “optionally substituted hydroxy” in the present specification means,unless otherwise specified, for example, “hydroxy”, “optionallysubstituted C₁₋₆ alkoxy”, “optionally substituted heterocyclyl-oxy”,“optionally substituted C₆₋₁₄ aryloxy”, “optionally substituted C₇₋₁₄aralkyloxy” or the like.

The “C₁₋₆ alkoxy” in the present specification means, unless otherwisespecified, for example, methoxy, ethoxy, propoxy, isopropoxy, butoxy,isobutoxy, tert-butoxy, pentyloxy, hexyloxy or the like.

The “C₁₋₆ alkoxy-C₁₋₆ alkoxy” in the present specification means, unlessotherwise specified, for example, methoxymethoxy, methoxyethoxy,ethoxymethoxy, ethoxyethoxy or the like.

The “heterocyclyl-oxy” in the present specification means hydroxylsubstituted by the below-mentioned “heterocyclic group”. Preferableexamples of the heterocyclyl-oxy include tetrahydropyranyloxy,thiazolyloxy, pyridyloxy, pyrazolyloxy, oxazolyloxy, thienyloxy,furyloxy and the like.

The “C₆₋₁₄ aryloxy” in the present specification means, unless otherwisespecified, for example, phenoxy, 1-naphthyloxy, 2-naphthyloxy or thelike.

The “C₇₋₁₄ aralkyloxy” in the present specification means, unlessotherwise specified, for example, benzyloxy, phenethyloxy or the like.

The “optionally substituted sulfanyl” in the present specificationmeans, unless otherwise specified, for example, “sulfanyl”, “optionallysubstituted C₁₋₆ alkylsulfanyl”, “optionally substitutedheterocyclyl-sulfanyl”, “optionally substituted C₆₋₁₄ arylsulfanyl”,“optionally substituted C₇₋₁₄ aralkylsulfanyl” or the like.

The “C₁₋₆ alkylsulfanyl” in the present specification means, unlessotherwise specified, for example, methylsulfanyl, ethylsulfanyl,propylsulfanyl, isopropylsulfanyl, butylsulfanyl, sec-butylsulfanyl,tert-butylsulfanyl or the like.

The “heterocyclyl-sulfanyl” in the present specification means sulfanylsubstituted by the below-mentioned “heterocyclic group”. Preferableexamples of the heterocyclyl-sulfanyl include tetrahydropyranylsulfanyl,thiazolylsulfanyl, pyridylsulfanyl, pyrazolylsulfanyl, oxazolylsulfanyl,thienylsulfanyl, furylsulfanyl and the like.

The “C₆₋₁₄ arylsulfanyl” in the present specification means, unlessotherwise specified, for example, phenylsulfanyl, 1-naphthylsulfanyl,2-naphthylsulfanyl or the like.

The “C₇₋₁₄ aralkylsulfanyl” in the present specification means, unlessotherwise specified, for example, benzylsulfanyl, phenethylsulfanyl orthe like.

The “heterocyclic group” in the present specification means, unlessotherwise specified, for example, a 5- to 14-membered (monocyclic,bicyclic or tricyclic) heterocyclic group containing, as aring-constituting atom besides carbon atom, 1 or 2 kinds of 1 to 4hetero atoms selected from a nitrogen atom, a sulfur atom and an oxygenatom, preferably (i) a 5- to 14-membered (preferably 5- to 10-membered)aromatic heterocyclic group, (ii) a 5- to 10-membered nonaromaticheterocyclic group or the like. Of these, a 5- or 6-membered aromaticheterocyclic group is preferable. Specifically, for example, aromaticheterocyclic groups such as thienyl (e.g., 2-thienyl, 3-thienyl), furyl(e.g., 2-furyl, 3-furyl), pyridyl (e.g., 2-pyridyl, 3-pyridyl,4-pyridyl), thiazolyl (e.g., 2-thiazolyl, 4-thiazolyl, 5-thiazolyl),oxazolyl (e.g., 2-oxazolyl, 4-oxazolyl, 5-oxazolyl), pyrazinyl,pyrimidinyl (e.g., 2-pyrimidinyl, 4-pyrimidinyl), pyrrolyl (e.g.,1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl), imidazolyl (e.g., 1-imidazolyl,2-imidazolyl, 4-imidazolyl), pyrazolyl (e.g., 1-pyrazolyl, 3-pyrazolyl,4-pyrazolyl), triazolyl (e.g., 1-triazolyl, 2-triazolyl), tetrazolyl,pyridazinyl (e.g., 3-pyridazinyl, 4-pyridazinyl), isothiazolyl (e.g.,3-isothiazolyl, 4-isothiazolyl, 5-isothiazolyl), isoxazolyl (e.g.,3-isoxazolyl, 4-isoxazolyl, 5-isoxazolyl), indolyl (e.g., 1-indolyl,2-indolyl, 3-indolyl), 2-benzothiazolyl, 2-benzoxazolyl, benzimidazolyl(e.g., 1-benzimidazolyl, 2-benzimidazolyl), benzo[b]thienyl (e.g.,2-benzo[b]thienyl, 3-benzo[b]thienyl), benzo[b]furyl (e.g.,2-benzo[b]furanyl, 3-benzo[b]furanyl), quinolyl (e.g., 2-quinolyl,3-quinolyl, 4-quinolyl, 5-quinolyl, 8-quinolyl), isoquinolyl (e.g.,1-isoquinolyl, 3-isoquinolyl, 4-isoquinolyl, 5-isoquinolyl),pyrazolopyridinyl (e.g., pyrazolo[1,5-a]pyridin-3-yl) and the like;

for example, nonaromatic heterocyclic groups such as pyrrolidinyl (e.g.,1-pyrrolidinyl, 2-pyrrolidinyl, 3-pyrrolidinyl), oxazolidinyl (e.g.,2-oxazolidinyl), imidazolinyl (e.g., 1-imidazolinyl, 2-imidazolinyl,4-imidazolinyl), piperidyl (e.g., piperidino, 2-piperidyl, 3-piperidyl,4-piperidyl), piperazinyl (e.g., 1-piperazinyl, 2-piperazinyl),morpholinyl (e.g., 2-morpholinyl, 3-morpholinyl, morpholino),thiomorpholinyl (e.g., 2-thiomorpholinyl, 3-thiomorpholinyl,thiomorpholino), tetrahydrofuryl, tetrahydropyranyl and the like can bementioned.

The “optionally substituted cyclic group” in the present specificationmeans, unless otherwise specified, for example, “optionally substitutedC₆₋₁₄ aryl”, “optionally substituted C₃₋₈ cycloalkyl”, “optionallysubstituted C₃₋₈ cycloalkenyl”, “optionally substituted heterocyclicgroup” or the like.

The “optionally substituted ring” in the present specification means,unless otherwise specified, for example, an optionally substituted ringcorresponding to the above-mentioned “optionally substituted cyclicgroup”.

The “C₆₋₁₄ aromatic hydrocarbon” in the present specification means aring corresponding to the above-mentioned “C₆₋₁₄ aryl”.

The “C₃₋₈ cycloalkane” in the present specification means a ringcorresponding to the above-mentioned “C₃₋₈ cycloalkyl”.

The “C₃₋₈ cycloalkene” in the present specification means a ringcorresponding to the above-mentioned “C₃₋₈ cycloalkenyl”.

The “heterocycle” in the present specification means a ringcorresponding to the above-mentioned “heterocyclic group”.

The “nitrogen-containing aromatic heterocycle containing 1 to 2 nitrogenatoms” means, unless otherwise specified, for example, anitrogen-containing aromatic heterocycle containing, as aring-constituting atom besides carbon atom and 1 to 2 nitrogen atoms,one or two kinds of 1 to 3 hetero atoms selected from a sulfur atom andan oxygen atom. Specifically, for example, pyridine ring, pyridazinering, pyrimidine ring, pyrazine ring and the like can be mentioned.

The “C₁₋₆ alkyl-carbonyl” in the present specification means, unlessotherwise specified, for example, acetyl, isobutanoyl, isopentanoyl orthe like.

The “C₁₋₆ alkoxy-carbonyl” in the present specification means, unlessotherwise specified, for example, methoxycarbonyl, ethoxycarbonyl,propoxycarbonyl, tert-butoxycarbonyl or the like.

The “C₃₋₈ cycloalkyl-carbonyl” in the present specification means,unless otherwise specified, for example, cyclopentylcarbonyl,cyclohexylcarbonyl or the like.

The “C₆₋₁₄ aryl-carbonyl” in the present specification means, unlessotherwise specified, for example, benzoyl, 1-naphthoyl, 2-naphthoyl orthe like.

The “C₇₋₁₄ aralkyl-carbonyl” in the present specification means, unlessotherwise specified, for example, phenylacetyl, 2-phenylpropanoyl or thelike.

The “C₆₋₁₄ aryloxy-carbonyl” in the present specification means, unlessotherwise specified, for example, phenoxycarbonyl, naphthyloxycarbonylor the like.

The “C₇₋₁₄ aralkyloxy-carbonyl” in the present specification means,unless otherwise specified, for example, benzyloxycarbonyl,phenethyloxycarbonyl or the like.

The “nitrogen-containing heterocyclyl-carbonyl” in the presentspecification means, unless otherwise specified, for example,pyrrolidinylcarbonyl, piperidinocarbonyl or the like.

The “C₁₋₆ alkylsulfonyl” in the present specification means, unlessotherwise specified, for example, methylsulfonyl, ethylsulfonyl or thelike.

The “C₆₋₁₄ arylsulfonyl” in the present specification means, unlessotherwise specified, for example, phenylsulfonyl, 1-naphthylsulfonyl,2-naphthylsulfonyl or the like.

The “C₁₋₆ alkylsulfinyl” in the present specification means, unlessotherwise specified, for example, methylsulfinyl, ethylsulfinyl or thelike.

The “C₆₋₁₄ arylsulfinyl” in the present specification means, unlessotherwise specified, for example, phenylsulfinyl, 1-naphthylsulfinyl,2-naphthylsulfinyl or the like.

The “optionally esterified carboxyl” in the present specification means,unless otherwise specified, for example, carboxyl, C₁₋₆ alkoxy-carbonyl,C₆₋₁₄ aryloxy-carbonyl, C₇₋₁₄ aralkyloxy-carbonyl or the like.

The “optionally halogenated C₁₋₆ alkyl” in the present specificationmeans, unless otherwise specified, the above-mentioned “C₁₋₆ alkyl”optionally substituted by 1 to 5 of the above-mentioned “halogen atom”.For example, methyl, ethyl, propyl, isopropyl, butyl, tert-butyl,isobutyl, trifluoromethyl and the like can be mentioned.

The “optionally halogenated C₁₋₆ alkoxy” in the present specificationmeans, unless otherwise specified, the above-mentioned “C₁₋₆ alkoxy”optionally substituted by 1 to 5 of the above-mentioned “halogen atom”.For example, methoxy, ethoxy, isopropoxy, tert-butoxy, trifluoromethoxyand the like can be mentioned.

The “mono- or di-C₁₋₆ alkyl-amino” in the present specification means,unless otherwise specified, amino mono- or di-substituted by theabove-mentioned “C₁₋₆ alkyl”. For example, methylamino, ethylamino,propylamino, dimethylamino, diethylamino and the like can be mentioned.

The “mono- or di-C₆₋₁₄ aryl-amino” in the present specification means,unless otherwise specified, amino mono- or di-substituted by theabove-mentioned “C₆₋₁₄ aryl”. For example, phenylamino, diphenylamino,1-naphthylamino, 2-naphthylamino and the like can be mentioned.

The “mono- or di-C₇₋₁₄ aralkyl-amino” in the present specificationmeans, unless otherwise specified, amino mono- or di-substituted by theabove-mentioned “C₇₋₁₄ aralkyl”. For example, benzylamino,phenethylamino and the like can be mentioned.

The “N—C₁₋₆ alkyl-N—C₆₋₁₄ aryl-amino” in the present specificationmeans, unless otherwise specified, amino substituted by theabove-mentioned “C₁₋₆ alkyl” and the above-mentioned “C₆₋₁₄ aryl”. Forexample, N-methyl-N-phenylamino, N-ethyl-N-phenylamino and the like canbe mentioned.

The “N—C₁₋₆ alkyl-N—C₇₋₁₄ aralkyl-amino” in the present specificationmeans, unless otherwise specified, amino substituted by theabove-mentioned “C₁₋₆ alkyl” and the above-mentioned “C₇₋₁₄ aralkyl”.For example, N-methyl-N-benzylamino, N-ethyl-N-benzylamino and the likecan be mentioned.

The “C₁₋₆ alkyl-carbonylamino” in the present specification means,unless otherwise specified, amino substituted by the above-mentioned“C₁₋₆ alkyl-carbonyl”. For example, acetyl amino, propionylamino and thelike can be mentioned.

The “mono- or di-C₁₋₆ alkyl-carbamoyl” in the present specificationmeans, unless otherwise specified, carbamoyl mono- or di-substituted bythe above-mentioned “C₁₋₆ alkyl”. For example, methylcarbamoyl,ethylcarbamoyl, dimethylcarbamoyl, diethylcarbamoyl,ethylmethylcarbamoyl and the like can be mentioned.

The “mono- or di-C₆₋₁₄ aryl-carbamoyl” in the present specificationmeans, unless otherwise specified, carbamoyl mono- or di-substituted bythe above-mentioned “C₆₋₁₄ aryl”. For example, phenylcarbamoyl,1-naphthylcarbamoyl, 2-naphthylcarbamoyl and the like can be mentioned.

The “mono- or di-C₃₋₈ cycloalkyl-carbamoyl” in the present specificationmeans, unless otherwise specified, carbamoyl mono- or di-substituted bythe above-mentioned “C₃₋₈ cycloalkyl”. For example, cyclopropylcarbamoyland the like can be mentioned.

The “mono- or di-C₇₋₁₄ aralkyl-carbamoyl” in the present specificationmeans, unless otherwise specified, carbamoyl mono- or di-substituted bythe above-mentioned “C₇₋₁₄ aralkyl”. For example, benzylcarbamoyl andthe like can be mentioned.

The “N—C₁₋₆ alkyl-N—C₆₋₁₄ aryl-carbamoyl” in the present specificationmeans, unless otherwise specified, carbamoyl substituted by theabove-mentioned “C₁₋₆ alkyl” and “C₆₋₁₄ aryl”. For example,(n-butyl)(phenyl) carbamoyl and the like can be mentioned.

The “mono- or di-5- to 7-membered heterocyclyl-carbamoyl” in the presentspecification means, unless otherwise specified, carbamoyl mono- ordi-substituted by a 5- to 7-membered heterocyclic group. Here, examplesof the 5- to 7-membered heterocyclic group include a heterocyclic groupcontaining, as a ring-constituting atom besides carbon atom, 1 or 2kinds of 1 to 4 hetero atoms selected from a nitrogen atom, a sulfuratom and an oxygen atom can be mentioned. Preferable examples of the“mono- or di-5- to 7-membered heterocyclyl-carbamoyl” include2-pyridylcarbamoyl, 3-pyridylcarbamoyl, 4-pyridylcarbamoyl,2-thienylcarbamoyl, 3-thienylcarbamoyl and the like.

As the “mono- or di-C₁₋₆ alkyl-sulfamoyl” in the present specification,unless otherwise specified, sulfamoyl mono- or di-substituted by theabove-mentioned “C₁₋₆ alkyl” can be used. For example, methylsulfamoyl,ethylsulfamoyl, dimethylsulfamoyl, diethylsulfamoyl and the like can bementioned.

As the “mono- or di-C₆₋₁₄ aryl-sulfamoyl” in the present specification,unless otherwise specified, sulfamoyl mono- or di-substituted by theabove-mentioned “C₆₋₁₄ aryl” can be used. For example, phenylsulfamoyl,diphenylsulfamoyl, 1-naphthylsulfamoyl, 2-naphthylsulfamoyl and the likecan be mentioned.

The “mono- or di-C₇₋₁₄ aralkyl-sulfamoyl” in the present specificationmeans, unless otherwise specified, sulfamoyl mono- or di-substituted bythe above-mentioned “C₇₋₁₄ aralkyl”. For example, benzylsulfamoyl andthe like can be mentioned.

The “C₁₋₆ alkyl-carbonyloxy” in the present specification means, unlessotherwise specified, for example, methylcarbonyloxy, ethylcarbonyloxy orthe like.

The “C₁₋₆ alkylene” in the present specification means, unless otherwisespecified, for example, —CH₂—, —CH₂CH₂—, —CH₂CH₂CH₂—, —CH₂CH₂CH₂CH₂—,—CH₂CH₂CH₂CH₂CH₂—, —CH₂CH₂CH₂CH₂CH₂CH₂—, —CH(CH₃)—, —C(CH₃)₂—,—CH(CH₂CH₃)—, —C(CH₂CH₃)₂—, —CH(CH(CH₃)₂)—, —CH(CH₃)CH₂—, —CH₂CH(CH₃)—,—CH(CH₂CH₃)CH₂—, —CH₂CH(CH₂CH₃)— or the like. The “C₁₋₅ alkylene” in thepresent specification means C₁₋₅ alkylene from among the above-mentioned“C₁₋₆ alkylene”.

Examples of the “optionally substituted C₁₋₁₀ (or C₁₋₆ or C₁₋₅) alkyl”,“optionally substituted C₂₋₁₀ (or C₂₋₆) alkenyl”, “optionallysubstituted C₂₋₁₀ (or C₂₋₆) alkynyl”, “optionally substituted C₁₋₆alkoxy”, “optionally substituted C₁₋₆ alkylsulfanyl” and “optionallysubstituted C₁₋₆ alkylene” in the present specification include “C₁₋₁₀(or C₁₋₆ or C₁₋₅) alkyl”, “C₂₋₆ alkenyl”, “C₂₋₁₀ (or C₂₋₆) alkynyl”,“C₂₋₁₀ (or C₂₋₆) alkoxy”, “C₁₋₆ alkylsulfanyl” and “C₁₋₆ alkylene”, eachof which optionally has, at substitutable position(s), 1 to 5substituents selected from

-   (1) a halogen atom;-   (2) hydroxy;-   (3) amino;-   (4) nitro;-   (5) cyano;-   (6) a heterocyclic group optionally substituted by 1 to 3    substituents selected from a halogen atom, hydroxy, oxo, amino,    nitro, cyano, an optionally halogenated C₁₋₆ alkyl, mono- or di-C₁₋₆    alkyl-amino, C₆₋₁₄ aryl, mono- or di-C₆₋₁₄ aryl-amino, C₃₋₈    cycloalkyl, C₁₋₆ alkoxy, C₁₋₆ alkoxy-C₁₋₆ alkoxy, C₁₋₆    alkylsulfanyl, C₁₋₆ alkylsulfinyl, C₁₋₆ alkylsulfonyl, optionally    esterified carboxyl, carbamoyl, thiocarbamoyl, mono- or di-C₁₋₆    alkyl-carbamoyl, mono- or di-C₆₋₁₄ aryl-carbamoyl, sulfamoyl, mono-    or di-C₁₋₆ alkyl-sulfamoyl and mono- or di-C₆₋₁₄ aryl-sulfamoyl;-   (7) mono- or di-C₁₋₆ alkyl-amino;-   (8) mono- or di-C₆₋₁₄ aryl-amino;-   (9) mono- or di-C₇₋₁₄ aralkyl-amino;-   (10) N—C₁₋₆ alkyl-N—C₆₋₁₄ aryl-amino;-   (11) N—C₁₋₆ alkyl-N—C₇₋₁₄ aralkyl-amino;-   (12) C₃₋₈ cycloalkyl;-   (13) optionally halogenated C₁₋₆ alkoxy;-   (14) C₁₋₆ alkylsulfanyl;-   (15) C₁₋₆ alkylsulfinyl;-   (16) C₁₋₆ alkylsulfonyl;-   (17) optionally esterified carboxyl;-   (18) C₁₋₆ alkyl-carbonyl;-   (19) C₃₋₈ cycloalkyl-carbonyl;-   (20) C₆₋₁₄ aryl-carbonyl;-   (21) carbamoyl;-   (22) thiocarbamoyl;-   (23) mono- or di-C₁₋₆ alkyl-carbamoyl;-   (24) mono- or di-C₆₋₁₄ aryl-carbamoyl;-   (25) N—C₁₋₆ alkyl-N—C₆₋₁₄ aryl-carbamoyl;-   (26) mono- or di-5- to 7-membered heterocyclyl-carbamoyl;-   (27) C₁₋₆ alkyl-carbonylamino optionally substituted by carboxyl;-   (28) C₆₋₁₄ aryloxy optionally substituted by 1 to 3 substituents    selected from a halogen atom, hydroxy, amino, nitro, cyano, an    optionally halogenated C₁₋₆ alkyl, mono- or di-C₁₋₆ alkyl-amino,    C₆₋₁₄ aryl, mono- or di-C₆₋₁₄ aryl-amino, C₃₋₈ cycloalkyl, C₁₋₆    alkoxy, C₁₋₆ alkoxy-C₁₋₆ alkoxy, C₁₋₆ alkylsulfanyl, C₁₋₆    alkylsulfinyl, C₁₋₆ alkylsulfonyl, optionally esterified carboxyl,    carbamoyl, thiocarbamoyl, mono- or di-C₁₋₆ alkyl-carbamoyl, mono- or    di-C₆₋₁₄ aryl-carbamoyl, sulfamoyl, mono- or di-C₁₋₆ alkyl-sulfamoyl    and mono- or di-C₆₋₁₄ aryl-sulfamoyl;-   (29) a C₆₋₁₄ aryl optionally substituted by 1 to 3 substituents    selected from a halogen atom, hydroxy, amino, nitro, cyano, an    optionally halogenated C₁₋₆ alkyl, mono- or di-C₁₋₆ alkyl-amino,    C₆₋₁₄ aryl, mono- or di-C₆₋₁₄ aryl-amino, C₃₋₈ cycloalkyl, C₁₋₆    alkoxy, C₁₋₆ alkoxy-C₁₋₆ alkoxy, C₁₋₆ alkylsulfanyl, C₁₋₆    alkylsulfinyl, C₁₋₆ alkylsulfonyl, optionally esterified carboxyl,    carbamoyl, thiocarbamoyl, mono- or di-C₁₋₆ alkyl-carbamoyl, mono- or    di-C₆₋₁₄ aryl-carbamoyl, sulfamoyl, mono- or di-C₁₋₆ alkyl-sulfamoyl    and mono- or di-C₆₋₁₄ aryl-sulfamoyl;-   (30) heterocyclyl-oxy;-   (31) sulfamoyl;-   (32) mono- or di-C₁₋₆ alkyl-sulfamoyl;-   (33) mono- or di-C₆₋₁₄ aryl-sulfamoyl;-   (34) C₇₋₁₄ aralkyloxy optionally substituted by 1 to 3 substituents    selected from a halogen atom, hydroxy, amino, nitro, cyano, an    optionally halogenated C₁₋₆ alkyl, mono- or di-C₁₋₆ alkyl-amino,    C₆₋₁₄ aryl, mono- or di-C₆₋₁₄ aryl-amino, C₃₋₈ cycloalkyl, C₁₋₆    alkoxy, C₁₋₆ alkoxy-C₁₋₆ alkoxy, C₁₋₆ alkylsulfanyl, C₁₋₆    alkylsulfinyl, C₁₋₆ alkylsulfonyl, optionally esterified carboxyl,    carbamoyl, thiocarbamoyl, mono- or di-C₁₋₆ alkyl-carbamoyl, mono- or    di-C₆₋₁₄ aryl-carbamoyl, sulfamoyl, mono- or di-C₁₋₆ alkyl-sulfamoyl    and mono- or di-C₆₋₁₄ aryl-sulfamoyl;-   (35) C₁₋₆ alkyl-carbonyloxy;-   (36) C₁₋₆ alkoxy-carbonyl;    and the like. When the number of the substituents is plural, the    respective substituents may be the same or different.

Examples of the “optionally substituted C₃₋₈ cycloalkyl”, “optionallysubstituted C₃₋₈ cycloalkenyl”, “optionally substituted C₆₋₁₄ aryl”,“optionally substituted C₇₋₁₄ aralkyl”, “optionally substitutedheterocyclic group”, “optionally substituted heterocyclyl-oxy”,“optionally substituted C₆₋₁₄ aryloxy”, “optionally substituted C₇₋₁₄aralkyloxy”, “optionally substituted heterocyclyl-sulfanyl”, “optionallysubstituted C₆₋₁₄ arylsulfanyl” and “optionally substituted C₇₋₁₄aralkylsulfanyl” in the present specification include “C₃₋₈ cycloalkyl”,“C₃₋₈ cycloalkenyl”, “C₆₋₁₄ aryl”, “C₇₋₁₄ aralkyl”, “heterocyclicgroup”, “heterocyclyl-oxy”, “C₆₋₁₄ aryloxy”, “C₇₋₁₄ aralkyloxy”,“heterocyclyl-sulfanyl”, “C₇₋₁₄ arylsulfanyl” and “C₇₋₁₄aralkylsulfanyl”, each of which optionally have, at substitutableposition(s), 1 to 5 substituents selected from

-   (1) a halogen atom;-   (2) hydroxy;-   (3) amino;-   (4) nitro;-   (5) cyano;-   (6) optionally substituted C₁₋₆ alkyl;-   (7) optionally substituted C₂₋₆ alkenyl;-   (8) optionally substituted C₂₋₆ alkynyl;-   (9) C₆₋₁₄ aryl optionally substituted by 1 to 3 substituents    selected from a halogen atom, hydroxy, amino, nitro, cyano, an    optionally halogenated C₁₋₆ alkyl, mono- or di-C₁₋₆ alkyl-amino,    C₆₋₁₄ aryl, mono- or di-C₆₋₁₄ aryl-amino, C₃₋₈ cycloalkyl, C₁₋₆    alkoxy, C₁₋₆ alkoxy-C₁₋₆ alkoxy, C₁₋₆ alkylsulfanyl, C₁₋₆    alkylsulfinyl, C₁₋₆ alkylsulfonyl, optionally esterified carboxyl,    carbamoyl, thiocarbamoyl, mono- or di-C₁₋₆ alkyl-carbamoyl, mono- or    di-C₆₋₁₄ aryl-carbamoyl, sulfamoyl, mono- or di-C₁₋₆ alkyl-sulfamoyl    and mono- or di-C₆₋₁₄ aryl-sulfamoyl;-   (10) C₆₋₁₄ aryloxy optionally substituted by 1 to 3 substituents    selected from a halogen atom, hydroxy, amino, nitro, cyano, an    optionally halogenated C₁₋₆ alkyl, mono- or di-C₁₋₆ alkyl-amino,    C₆₋₁₄ aryl, mono- or di-C₆₋₁₄ aryl-amino, C₃₋₈ cycloalkyl, C₁₋₆    alkoxy, C₁₋₆ alkoxy-C₁₋₆ alkoxy, C₁₋₆ alkylsulfanyl, C₁₋₆    alkylsulfinyl, C₁₋₆ alkylsulfonyl, optionally esterified carboxyl,    carbamoyl, thiocarbamoyl, mono- or di-C₁₋₆ alkyl-carbamoyl, mono- or    di-C₆₋₁₄ aryl-carbamoyl, sulfamoyl, mono- or di-C₁₋₆ alkyl-sulfamoyl    and mono- or di-C₆₋₁₄ aryl-sulfamoyl;-   (11) C₇₋₁₄ aralkyloxy optionally substituted by 1 to 3 substituents    selected from a halogen atom, hydroxy, amino, nitro, cyano, an    optionally halogenated C₁₋₆ alkyl, mono- or di-C₁₋₆ alkyl-amino,    C₆₋₁₄ aryl, mono- or di-C₆₋₁₄ aryl-amino, C₃₋₈ cycloalkyl, C₁₋₆    alkoxy, C₁₋₆ alkoxy-C₁₋₆ alkoxy, C₁₋₆ alkylsulfanyl, C₁₋₆    alkylsulfinyl, C₁₋₆ alkylsulfonyl, optionally esterified carboxyl,    carbamoyl, thiocarbamoyl, mono- or di-C₁₋₆ alkyl-carbamoyl, mono- or    di-C₆₋₁₄ aryl-carbamoyl, sulfamoyl, mono- or di-C₁₋₆ alkyl-sulfamoyl    and mono- or di-C₆₋₁₄ aryl-sulfamoyl;-   (12) a heterocyclic group optionally substituted by 1 to 3    substituents selected from a halogen atom, hydroxy, amino, nitro,    cyano, an optionally halogenated C₁₋₆ alkyl, mono- or di-C₁₋₆    alkyl-amino, C₆₋₁₄ aryl, mono- or di-C₆₋₁₄ aryl-amino, C₃₋₈    cycloalkyl, C₁₋₆ alkoxy, C₁₋₆ alkoxy-C₁₋₆ alkoxy, C₁₋₆    alkylsulfanyl, C₁₋₆ alkylsulfinyl, C₁₋₆ alkylsulfonyl, optionally    esterified carboxyl, carbamoyl, thiocarbamoyl, mono- or di-C₁₋₆    alkyl-carbamoyl, mono- or di-C₆₋₁₄ aryl-carbamoyl, sulfamoyl, mono-    or di-C₁₋₆ alkyl-sulfamoyl and mono- or di-C₆₋₁₄ aryl-sulfamoyl;-   (13) mono- or di-C₁₋₆ alkyl-amino;-   (14) mono- or di-C₆₋₁₄ aryl-amino;-   (15) mono- or di-C₇₋₁₄ aralkyl-amino;-   (16) N—C₁₋₆ alkyl-N—C₆₋₁₄ aryl-amino;-   (17) N—C₁₋₆ alkyl-N—C₇₋₁₄ aralkyl-amino;-   (18) C₃₋₈ cycloalkyl;-   (19) optionally substituted C₁₋₆ alkoxy;-   (20) optionally substituted C₁₋₆ alkylsulfanyl;-   (21) C₁₋₆ alkylsulfinyl;-   (22) C₁₋₆ alkylsulfonyl;-   (23) optionally esterified carboxyl;-   (24) C₁₋₆ alkyl-carbonyl;-   (25) C₃₋₈ cycloalkyl-carbonyl;-   (26) C₆₋₁₄ aryl-carbonyl;-   (27) carbamoyl;-   (28) thiocarbamoyl;-   (29) mono- or di-C₁₋₆ alkyl-carbamoyl;-   (30) mono- or di-C₆₋₁₄ aryl-carbamoyl;-   (31) N—C₁₋₆ alkyl-N—C₆₋₁₄ aryl-carbamoyl;-   (32) mono- or di-5- to 7-membered heterocyclyl-carbamoyl;-   (33) sulfamoyl;-   (34) mono- or di-C₁₋₆ alkyl-sulfamoyl;-   (35) mono- or di-C₆₋₁₄ aryl-sulfamoyl;-   (36) C₁₋₆ alkyl-carbonylamino optionally substituted by carboxyl;-   (37) heterocyclyl-oxy;-   (38) C₁₋₆ alkyl-carbonyloxy;-   (39) C₁₋₆ alkoxy-carbonyl;-   and the like. When the number of the substituents is plural, the    respective substituents may be the same or different.

The “optionally substituted amino” in the present specification means,unless otherwise specified, amino optionally substituted by 1 or 2substituents selected from

-   (1) optionally substituted C₁₋₆ alkyl;-   (2) optionally substituted C₂₋₆ alkenyl;-   (3) optionally substituted C₂₋₆ alkynyl;-   (4) optionally substituted C₃₋₈ cycloalkyl;-   (5) optionally substituted C₆₋₁₄ aryl;-   (6) optionally substituted C₁₋₆ alkoxy;-   (7) optionally substituted acyl;-   (8) optionally substituted heterocyclic group (preferably furyl,    pyridyl, thienyl, pyrazolyl, thiazolyl, oxazolyl);-   (9) sulfamoyl;-   (10) mono- or di-C₁₋₆ alkyl-sulfamoyl;-   (11) mono- or di-C₆₋₁₄ aryl-sulfamoyl;    or the like. In addition, when the “optionally substituted amino” is    amino substituted by two substituents, these substituents may be    same or different, and these substituents may form, together with    the adjacent nitrogen atom, a nitrogen-containing heterocycle.    Examples of the “nitrogen-containing heterocycle” include a 5- to    7-membered nitrogen-containing heterocycle optionally containing, as    a ring-constituting atom besides carbon atom, at least one nitrogen    atom, and further, 1 or 2 hetero atoms selected from an oxygen atom,    a sulfur atom and a nitrogen atom. Preferable examples of the    nitrogen-containing heterocycle include pyrrolidine, imidazolidine,    pyrazolidine, piperidine, piperazine, morpholine, thiomorpholine,    thiazolidine, oxazolidine and the like.

The “optionally substituted aminocarbonyl” in the present specificationmeans, unless otherwise specified, aminocarbonyl wherein the “optionallysubstituted amino” moiety is the above-mentioned “optionally substitutedamino”.

The “optionally substituted acyl” in the present specification means,unless otherwise specified, a group represented by the formula: —COR¹⁸,—CO—OR¹⁸, —SO₂R¹⁸, —SOR¹⁸, —PO(OR¹⁸)(OR¹⁹), —CO—NR^(18a)R^(19a) and—CS—NR^(18a)R^(19a) wherein R¹⁸ and R¹⁹ are the same or different andeach is a hydrogen atom, an optionally substituted hydrocarbon group oran optionally substituted heterocyclic group, R^(18a) and R^(19a) arethe same or different and each is a hydrogen atom, an optionallysubstituted hydrocarbon group or an optionally substituted heterocyclicgroup, R^(18a) and R^(19a) may form, together with the adjacent nitrogenatom, an optionally substituted nitrogen-containing heterocycle, or thelike.

Examples of the “nitrogen-containing heterocycle” of the “optionallysubstituted nitrogen-containing heterocycle” formed by R^(18a) andR^(19a) together with the adjacent nitrogen atom include a 5- to7-membered nitrogen-containing heterocycle optionally containing, as aring-constituting atom besides carbon atom, at least one nitrogen atom,and further, 1 or 2 hetero atoms selected from an oxygen atom, a sulfuratom and a nitrogen atom. Preferable examples of the nitrogen-containingheterocycle include pyrrolidine, imidazolidine, pyrazolidine,piperidine, piperazine, morpholine, thiomorpholine, thiazolidine,oxazolidine and the like.

The nitrogen-containing heterocycle may have 1 or 2 substituents atsubstitutable position(s). Examples of such substituent include hydroxy,an optionally halogenated C₁₋₆ alkyl, C₆₋₁₄ aryl, C₇₋₁₄ aralkyl and thelike. When the number of the substituents is 2, these substituents maybe the same or different.

Preferable examples of the “optionally substituted acyl” include

-   formyl;-   carboxyl;-   carbamoyl;-   C₁₋₆ alkyl-carbonyl;-   C₁₋₆ alkoxy-carbonyl;-   C₃₋₈ cycloalkyl-carbonyl;-   C₆₋₁₄ aryl-carbonyl;-   C₇₋₁₄ aralkyl-carbonyl;-   C₆₋₁₄ aryloxy-carbonyl;-   C₇₋₁₄ aralkyloxy-carbonyl;-   mono- or di-C₁₋₆ alkyl-carbamoyl;-   mono- or di-C₆₋₁₄ aryl-carbamoyl;-   mono- or di-C₃₋₈ cycloalkyl-carbamoyl;-   mono- or di-C₇₋₁₄ aralkyl-carbamoyl;-   C₁₋₆ alkylsulfonyl;-   C₆₋₁₄ arylsulfonyl optionally substituted by nitro;-   nitrogen-containing heterocyclyl-carbonyl;-   C₁₋₆ alkylsulfinyl;-   C₆₋₁₄ arylsulfinyl;-   thiocarbamoyl;-   sulfamoyl;-   mono- or di-C₁₋₆ alkyl-sulfamoyl;-   mono- or di-C₆₋₁₄ aryl-sulfamoyl;-   mono- or di-C₇₋₁₄ aralkyl-sulfamoyl;    and the like.

The definition of each symbol in the formula (1) is explained in detailin the following.

R¹ is a hydrogen atom or an optionally substituted C₁₋₆ alkyl group.

R¹ is preferably a hydrogen atom or a C₁₋₆ alkyl group.

R¹ is more preferably a hydrogen atom or a C₁₋₃ alkyl group (preferablymethyl).

R¹ is particularly preferably a hydrogen atom.

R² and R³ are each independently a hydrogen atom or an optionallysubstituted C₁₋₆ alkyl group, or R² and R³ in combination optionallyform, together with the adjacent carbon atom, an optionally substitutedring.

R² and R³ are preferably each independently a hydrogen atom or a C₁₋₆alkyl group (e.g., methyl).

R² and R³ are more preferably both hydrogen atoms.

Examples of the “optionally substituted ring” formed by R² and R³ incombination together with the adjacent carbon atom include a ringrepresented by

wherein R²⁰ is an optionally substituted C₁₋₆ alkyl group, and the like.

Examples of the substituent for “ring” of the “optionally substitutedring” formed by R² and R³ in combination together with the adjacentcarbon atom include those similar to the substituent for the“heterocyclic group” of the above-mentioned “optionally substitutedheterocyclic group”.

X is a bond or an optionally substituted C₁₋₆ alkylene group.

The “C₁₋₆ alkylene group” of the “optionally substituted C₁₋₆ alkylenegroup” for X is preferably a C₁₋₅ alkylene group, more preferably —CH₂—,—CH(CH₃)—, —CH(CH₂CH₃)—, —CH(CH₂CH₂CH₃)— or —CH(CH(CH₃)₂)—.

In another embodiment, the “C₁₋₆ alkylene group” of the “optionallysubstituted C₁₋₆ alkylene group” for X is more preferably —CH₂—,—CH(CH₃)—, —CH(CH₂CH₃)—, —CH(CH₂CH₂CH₃)—, —CH(CH(CH₃)₂)—, —CH(C(CH₃)₃)—,—CH(CH₂CH₂CH₂CH₃)—, —CH(CH(CH₂CH₃)₂)— or —CH₂CH₂—.

In yet another embodiment, the “C₁₋₆ alkylene group” of the “optionallysubstituted C₁₋₆ alkylene group” for X is more preferably —CH₂—,—CH(CH₃)—, —CH(CH₂CH₃)—, —CH(CH₂CH₂CH₃)—, —CH(CH(CH₃)₂)—, —CH(C(CH₃)₃)—,—CH(CH₂CH₂CH₂CH₃)— or —CH(CH(CH₂CH₃)₂)—.

X is preferably an optionally substituted C₁₋₆ alkylene group(preferably an optionally substituted C₁₋₅ alkylene group)

X is more preferably a C₁₋₆ alkylene group (preferably a C₁₋₅ alkylenegroup, more preferably —CH₂—, —CH(CH₃)—, —CH(CH₂CH₃)—, —CH(CH₂CH₂CH₃)—or —CH(CH(CH₃)₂)—) optionally substituted by 1 to 3 substituentsselected from

-   (1) hydroxy,-   (2) cyano,-   (3) carbamoyl,-   (4) C₁₋₆ alkoxy (e.g., methoxy),-   (5) C₁₋₆ alkylsulfanyl (e.g., methylsulfanyl),-   (6) C₁₋₆ alkylsulfonyl (e.g., methylsulfonyl),-   (7) mono- or di-C₁₋₆ alkyl-amino (e.g., dimethylamino),-   (8) C₃₋₈ cycloalkyl (e.g., cyclopropyl),-   (9) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by 1 to 3    substituents selected from optionally halogenated C₁₋₆ alkoxy (e.g.,    methoxy) (preferably optionally substituted by 1 to 3 halogen atoms    (e.g., a fluorine atom)), and-   (10) a heterocyclic group (preferably a 5- or 6-membered aromatic    heterocyclic group) (e.g., pyridyl, isoxazolyl, pyrazolyl)    optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl).

In another embodiment, X is more preferably a C₁₋₆ alkylene group(preferably —CH₂—, —CH(CH₃)—, —CH(CH₂CH₃)—, —CH(CH₂CH₂CH₃)—,—CH(CH(CH₃)₂)—, —CH(C(CH₃)₃)—, —CH(CH₂CH₂CH₂CH₃)—, —CH(CH(CH₂CH₃)₂)— or—CH₂CH₂—) optionally substituted by 1 to 5 substituents selected from

-   (1) a halogen atom (e.g., a fluorine atom),-   (2) hydroxy,-   (3) amino,-   (4) cyano,-   (5) carbamoyl,-   (6) mono- or di-C₁₋₆ alkyl-carbamoyl (e.g., methylcarbamoyl,    dimethylcarbamoyl),-   (7) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₁₋₆ alkoxy (e.g., methoxy),-   (8) C₁₋₆ alkylsulfanyl (e.g., methylsulfanyl),-   (9) C₁₋₆ alkylsulfinyl (e.g., methylsulfinyl),-   (10) C₁₋₆ alkylsulfonyl (e.g., methylsulfonyl),-   (11) mono- or di-C₁₋₆ alkyl-amino (e.g., dimethylamino),-   (12) C₃₋₈ cycloalkyl (e.g., cyclopropyl),-   (13) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by 1 to 3    substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom, a bromine atom),    -   (ii) hydroxy, and    -   (iii) optionally halogenated C₁₋₆ alkoxy (e.g., methoxy)        (preferably optionally substituted by 1 to 3 halogen atoms        (e.g., a fluorine atom)),-   (14) a heterocyclic group (preferably a 4- to 10-membered    heterocyclic group) (e.g., pyridyl, isoxazolyl, pyrazolyl,    pyrrolidinyl, triazolyl, oxetanyl, tetrahydrofuryl,    tetrahydropyranyl, dihydroisoindolyl) optionally substituted by 1 to    3 substituents selected from    -   (i) C₁₋₆ alkyl (e.g., methyl),    -   (ii) hydroxy, and    -   (iii) oxo,-   (15) C₃₋₈ cycloalkyloxy (e.g., cyclopentyloxy),-   (16) optionally halogenated heterocyclyl-oxy (e.g., pyridyloxy)    (preferably optionally substituted by 1 to 3 halogen atoms (e.g., a    bromine atom)),-   (17) C₁₋₆ alkyl-carbonyloxy (e.g., acetoxy),-   (18) C₁₋₆ alkyl(diaryl)silyloxy (e.g., tert-butyl(diphenyl)    silyloxy),-   (19) C₁₋₆ alkyl-carbonyl (e.g., acetyl), and-   (20) C₃₋₈ cycloalkyl-carbonyl (e.g., cyclopropylcarbonyl), or a    bond.

In yet another embodiment, X is more preferably a C₁₋₆ alkylene group(preferably —CH₂—, —CH(CH₃)—, —CH(CH₂CH₃)—, —CH(CH₂CH₂CH₃)—,—CH(CH(CH₃)₂)—, —CH(C(CH₃)₃)—, —CH(CH₂CH₂CH₂CH₃)— or —CH(CH(CH₂CH₃)₂))optionally substituted by 1 to 5 substituents selected from

-   (1) a halogen atom (e.g., a fluorine atom),-   (2) hydroxy,-   (3) amino,-   (4) cyano,-   (5) carbamoyl,-   (6) mono- or di-C₁₋₆ alkyl-carbamoyl (e.g., methylcarbamoyl,    dimethylcarbamoyl),-   (7) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₁₋₆ alkoxy (e.g., methoxy),-   (8) C₁₋₆ alkylsulfanyl (e.g., methylsulfanyl),-   (9) C₁₋₆ alkylsulfinyl (e.g., methylsulfinyl),-   (10) C₁₋₆ alkylsulfonyl (e.g., methylsulfonyl),-   (11) mono- or di-C₁₋₆ alkyl-amino (e.g., dimethylamino),-   (12) C₃₋₈ cycloalkyl (e.g., cyclopropyl),-   (13) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by 1 to 3    substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom, a bromine atom),    -   (ii) hydroxy, and    -   (iii) optionally halogenated C₁₋₆ alkoxy (e.g., methoxy)        (preferably optionally substituted by 1 to 3 halogen atoms        (e.g., a fluorine atom)),-   (14) a heterocyclic group (preferably a 4- to 10-membered    heterocyclic group) (e.g., pyridyl, isoxazolyl, pyrazolyl,    pyrrolidinyl, triazolyl, oxetanyl, tetrahydrofuryl,    tetrahydropyranyl, dihydroisoindolyl) optionally substituted by 1 to    3 substituents selected from    -   (i) C₁₋₆ alkyl (e.g., methyl),    -   (ii) hydroxy, and    -   (iii) oxo,-   (15) C₃₋₈ cycloalkyloxy (e.g., cyclopentyloxy),-   (16) optionally halogenated heterocyclyl-oxy (e.g., pyridyloxy)    (preferably optionally substituted by 1 to 3 halogen atoms (e.g., a    bromine atom)),-   (17) C₁₋₆ alkyl-carbonyloxy (e.g., acetoxy),-   (18) C₁₋₆ alkyl(diaryl)silyloxy (e.g.,    tert-butyl(diphenyl)silyloxy),-   (19) C₁₋₆ alkyl-carbonyl (e.g., acetyl), and-   (20) C₃₋₈ cycloalkyl-carbonyl (e.g., cyclopropylcarbonyl).

X is still more preferably a C₁₋₆ alkylene group (preferably a C₁₋₅alkylene group, more preferably —CH(CH₃)— or —CH(CH(CH₃)₂)—) optionallysubstituted by 1 to 3 substituents selected from

-   (1) hydroxy, and-   (2) C₁₋₆ alkoxy (e.g., methoxy).

A is an optionally substituted cyclic group.

The “optionally substituted cyclic group” for A is “optionallysubstituted C₆ ₁₄ aryl”, “optionally substituted C₃₋₈ cycloalkyl”,“optionally substituted C₃₋₈ cycloalkenyl” or “optionally substitutedheterocyclic group”. The “cyclic group” is optionally fused, forexample, with a C₆₋₁₄ aromatic hydrocarbon, a C₃₋₈ cycloalkane, a C₃₋₈cycloalkene, a heterocycle or the like.

The “cyclic group” of the “optionally substituted cyclic group” for A ispreferably a C₆₋₁₄ aryl group or a 5- or 6-membered aromaticheterocyclic group, more preferably a C₆₋₁₀ aryl group or a 5- or6-membered nitrogen-containing aromatic heterocyclic group, still morepreferably phenyl, pyridazinyl, pyridyl, pyrimidinyl, isoxazolyl orpyrazolyl, particularly preferably phenyl.

A is preferably a C₆₋₁₀ aryl group or a 5- or 6-memberednitrogen-containing aromatic heterocyclic group, each of which isoptionally substituted, more preferably an optionally substituted phenylgroup.

A is more preferably a C₆₋₁₀ aryl group or a 5- or 6-membered aromaticheterocyclic group (preferably a C₆₋₁₀ aryl group or a 5- or 6-memberednitrogencontaining aromatic heterocyclic group, more preferably phenyl,pyridazinyl, pyridyl, pyrimidinyl, isoxazolyl or pyrazolyl, particularlypreferably phenyl), each of which is optionally substituted by 1 to 3substituents selected from

-   (1) a halogen atom (e.g., a fluorine atom),-   (2) hydroxy,-   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, isopropyl)    (preferably optionally substituted by 1 to 3 halogen atoms (e.g., a    fluorine atom)),-   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),-   (5) C₁₋₆ alkoxy (e.g., methoxy) optionally substituted by 1 to 3    substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),-   (6) C₆₋₁₄ aryl (e.g., phenyl), and-   (7) a heterocyclic group (preferably a 5- or 6-membered heterocyclic    group) (e.g., pyrazolyl, dihydropyranyl, tetrahydropyranyl)    optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl).

In another embodiment, A is more preferably a C₆₋₁₀ aryl group, a 4- to10membered heterocyclic group or a C₃₋₈ cycloalkyl group (preferablyphenyl, pyridazinyl, pyridyl, pyrimidinyl, isoxazolyl, pyrazolyl,oxetanyl, pyrrolidinyl, tetrahydrofuryl, imidazolyl, triazolyl, thienyl,tetrahydropyranyl, imidazo[1,2-a]pyridyl, benzodioxolyl,pyrazolo[1,5-a]pyridyl, dihydroisoindolyl or cyclopropyl, morepreferably phenyl), each of which is optionally substituted by 1 to 3substituents selected from

-   (1) a halogen atom (e.g., a fluorine atom, a chlorine atom, a    bromine atom),-   (2) hydroxy,-   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, ethyl,    isopropyl) (preferably optionally substituted by 1 to 3 halogen    atoms (e.g., a fluorine atom)),-   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),-   (5) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),-   (6) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by optionally    halogenated C₁₋₆ alkoxy (e.g., methoxy) (preferably optionally    substituted by 1 to 3 halogen atoms (e.g., a fluorine atom)),-   (7) a heterocyclic group (preferably a 4- to 6-membered heterocyclic    group) (e.g., azetidinyl, pyrazolyl, pyrrolyl, pyrrolidinyl,    triazolyl, dihydropyranyl, tetrahydropyranyl) optionally substituted    by 1 to 3 C₁₋₆ alkyl (e.g., methyl),-   (8) C₃₋₈ cycloalkyl (e.g., cyclopropyl), and-   (9) oxo.

In yet another embodiment, A is more preferably a C₆₋₁₀ aryl group or a5- to 10-membered aromatic heterocyclic group (preferably phenyl,pyridazinyl, pyridyl, pyrimidinyl, isoxazolyl, pyrazolyl, imidazolyl,triazolyl, thienyl, imidazo[1,2-a]pyridyl or pyrazolo[1,5-a]pyridyl,more preferably phenyl), each of which is optionally substituted by 1 to3 substituents selected from

-   (1) a halogen atom (e.g., a fluorine atom, a chlorine atom, a    bromine atom),-   (2) hydroxy,-   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, ethyl,    isopropyl) (preferably optionally substituted by 1 to 3 halogen    atoms (e.g., a fluorine atom)),-   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),-   (5) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),-   (6) C₆₋₁₄ aryl (e.g., phenyl),-   (7) a heterocyclic group (preferably a 4- to 6-membered heterocyclic    group) (e.g., azetidinyl, pyrazolyl, pyrrolyl, pyrrolidinyl,    triazolyl, dihydropyranyl, tetrahydropyranyl) optionally substituted    by 1 to 3 C₁₋₆ alkyl (e.g., methyl), and-   (8) C₃₋₈ cycloalkyl (e.g., cyclopropyl).

In yet another embodiment, A is more preferably a C₆₋₁₀ aryl group(preferably phenyl), optionally substituted by 1 to 3 substituentsselected from

-   (1) a halogen atom (e.g., a fluorine atom, a chlorine atom, a    bromine atom),-   (2) hydroxy,-   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, isopropyl)    (preferably optionally substituted by 1 to 3 halogen atoms (e.g., a    fluorine atom)),-   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),-   (5) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),-   (6) C₆₋₁₄ aryl (e.g., phenyl),-   (7) a heterocyclic group (preferably a 4- to 6-membered heterocyclic    group) (e.g., azetidinyl, pyrazolyl, pyrrolyl, pyrrolidinyl,    triazolyl, dihydropyranyl, tetrahydropyranyl) optionally substituted    by 1 to 3 C₁₋₆ alkyl (e.g., methyl), and-   (8) C₃₋₈ cycloalkyl (e.g., cyclopropyl).

A is particularly preferably a C₆₋₁₀ aryl group (e.g., phenyl)optionally substituted by 1 to 3 substituents selected from

-   (1) a halogen atom (e.g., a fluorine atom), and-   (2) C₁₋₆ alkoxy (e.g., methoxy) optionally substituted by 1 to 3    halogen atoms (e.g., a fluorine atom).

Preferable examples of the group represented by

include a group represented by

-   -   wherein    -   R²¹ is a hydrogen atom, an optionally substituted C₁₋₅ alkyl        group, a C₃₋₈ cycloalkyl group, a carbamoyl group or a cyano        group, and    -   R²² is a hydrogen atom or a substituent.

Another preferable examples of the group represented by

include a group represented by

-   -   wherein    -   R²¹ is a hydrogen atom, an optionally substituted C₁₋₅ alkyl        group, a C₃₋₈ cycloalkyl group, a carbamoyl group, a cyano group        or an optionally substituted heterocyclic group,    -   R²² is a hydrogen atom or a substituent, and    -   p is an integer of 1 to 5.

The “substituent” for R²² corresponds to the “substituent” of the“optionally substituted cyclic group” for A.

In another embodiment, another preferable examples of the grouprepresented by

include a group represented by

-   -   wherein    -   R²¹ is a hydrogen atom, an optionally substituted C₁₋₆ alkyl        group, a C₃₋₈ cycloalkyl group, an optionally substituted        carbamoyl group, a cyano group, an optionally substituted        heterocyclic group, a C₁₋₆ alkyl-carbonyl group, a C₃₋₈        cycloalkyl-carbonyl group or an optionally substituted C₆₋₁₄        aryl group,

-   R²² is a hydrogen atom or a substituent, and

-   p is an integer of 1 to 5.

The “substituent” for R²² corresponds to the “substituent” of the“optionally substituted cyclic group” for A.

The group represented by

is more preferably

wherein

-   R²¹ is-   (1) cyano-   (2) carbamoyl-   (3) C₁₋₅ alkyl (e.g., methyl, ethyl, isopropyl, propyl) optionally    substituted by 1 to 3 substituents selected from    -   (i) hydroxy,    -   (ii) C₁₋₆ alkoxy (e.g., methoxy),    -   (iii) mono- or di-C₁₋₆ alkyl-amino (e.g., dimethylamino),    -   (iv) C₁₋₆ alkylsulfanyl (e.g., methylsulfanyl), and    -   (v) C₁₋₆ alkylsulfonyl (e.g., methylsulfonyl),-   (4) C₃₋₈ cycloalkyl (e.g., cyclopropyl), or-   (5) a heterocyclic group (preferably a 5- or 6-membered aromatic    heterocyclic group) (e.g., pyridyl, isoxazolyl, pyrazolyl)    optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl),-   R²² is-   (1) a halogen atom (e.g., a fluorine atom),-   (2) hydroxy,-   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, isopropyl)    (preferably optionally substituted by 1 to 3 halogen atoms (e.g., a    fluorine atom)),-   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),-   (5) C₁₋₆ alkoxy (e.g., methoxy) optionally substituted by 1 to 3    substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),-   (6) C₆₋₁₄ aryl (e.g., phenyl), or-   (7) a heterocyclic group (preferably a 5- or 6-membered heterocyclic    group) (e.g., pyrazolyl, dihydropyranyl, tetrahydropyranyl)    optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl), and-   p is an integer of 1 to 3.

In another embodiment, the group represented by

is more preferably

wherein

-   R²¹ is-   (1) cyano,-   (2) carbamoyl,-   (3) mono- or di-C₁₋₆ alkyl-carbamoyl (e.g., methylcarbamoyl,    dimethylcarbamoyl),-   (4) C₁₋₆ alkyl (e.g., methyl, ethyl, isopropyl, propyl, butyl,    tert-butyl, 1-ethylpropyl) optionally substituted by 1 to 5    substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom),    -   (ii) hydroxy,    -   (iii) amino,    -   (iv) cyano,    -   (v) C₃₋₈ cycloalkyl (e.g., cyclopropyl),    -   (vi) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally        substituted by 1 to 3 substituents selected from        -   (a) a halogen atom (e.g., a fluorine atom), and        -   (b) C₁₋₆ alkoxy (e.g., methoxy),    -   (vii) C₃₋₈ cycloalkyloxy (e.g., cyclopentyloxy),    -   (viii) mono- or di-C₁₋₆ alkyl-amino (e.g., dimethylamino),    -   (ix) C₁₋₆ alkylsulfanyl (e.g., methylsulfanyl),    -   (x) C₁₋₆ alkylsulfinyl (e.g., methylsulfinyl),    -   (xi) C₁₋₆ alkylsulfonyl (e.g., methylsulfonyl),    -   (xii) carbamoyl,    -   (xiii) mono- or di-C₁₋₆ alkyl-carbamoyl (e.g.,        dimethylcarbamoyl),    -   (xiv) a heterocyclic group (e.g., oxetanyl, pyrrolidinyl,        pyrazolyl, triazolyl, tetrahydropyranyl, dihydroisoindolyl)        optionally substituted by 1 to 3 substituents selected from        -   (a) hydroxy, and        -   (b) oxo,    -   (xv) C₁₋₆ alkyl-carbonyloxy (e.g., acetoxy),    -   (xvi) C₁₋₆ alkyl(diaryl)silyloxy (e.g.,        tert-butyl(diphenyl)silyloxy), and    -   (xvii) optionally halogenated heterocyclyl-oxy (e.g.,        pyridyloxy) (preferably optionally substituted by 1 to 3 halogen        atoms (e.g., a bromine atom)),-   (5) C₃₋₈ cycloalkyl (e.g., cyclopropyl),-   (6) a heterocyclic group (preferably a 4- to 6-membered heterocyclic    group) (e.g., pyridyl, isoxazolyl, pyrazolyl, oxetanyl,    tetrahydrofuryl, tetrahydropyranyl) optionally substituted by 1 to 3    C₁₋₆ alkyl (e.g., methyl),-   (7) C₁₋₆ alkyl-carbonyl (e.g., acetyl),-   (8) C₃₋₈ cycloalkyl-carbonyl (e.g., cyclopropylcarbonyl), or-   (9) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by 1 to 3    substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom, a bromine atom), and    -   (ii) hydroxy,-   R²² is-   (1) a halogen atom (e.g., a fluorine atom, a chlorine atom, a    bromine atom),-   (2) hydroxy,-   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, isopropyl)    (preferably optionally substituted by 1 to 3 halogen atoms (e.g., a    fluorine atom)),-   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),-   (5) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),-   (6) C₆₋₁₄ aryl (e.g., phenyl),-   (7) a heterocyclic group (preferably a 4- to 6-membered heterocyclic    group) (e.g., azetidinyl, pyrazolyl, pyrrolyl, pyrrolidinyl,    triazolyl, dihydropyranyl, tetrahydropyranyl) optionally substituted    by 1 to 3 C₁₋₆ alkyl (e.g., methyl), or-   (8) C₃₋₈ cycloalkyl (e.g., cyclopropyl), and-   p is an integer of 1 to 3.

The group represented by

is still more preferably a group represented by

wherein

-   R²¹ is a C₁₋₅ alkyl group (e.g., methyl, isopropyl) optionally    substituted by hydroxyl or C₁₋₆ alkoxy (e.g., methoxy),-   R²² is-   (1) a halogen atom (e.g., a fluorine atom), or-   (2) optionally halogenated C₁₋₆ alkoxy (e.g., methoxy) (preferably    optionally substituted by 1 to 3 halogen atoms (e.g., a fluorine    atom)), and-   p is an integer of 1 or 2.

Z¹ is a group represented by CR^(Z1) wherein R^(Z1) is a hydrogen atom,a halogen atom, an optionally substituted C₁₋₆ alkyl group, anoptionally substituted C₂₋₆ alkenyl group, an optionally substitutedC₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, anoptionally substituted amino group or a cyano group, or a nitrogen atom.

In another embodiment, Z¹ is a group represented by CR^(Z1) whereinR^(Z1) is a hydrogen atom, a halogen atom, an optionally substitutedC₁₋₆ alkyl group, an optionally substituted C₂₋₆ alkenyl group, anoptionally substituted C₂₋₆ alkynyl group, an optionally substitutedC₁₋₆ alkoxy group, an optionally substituted amino group, a cyano groupor an optionally substituted cyclic group, or a nitrogen atom.

Z¹ is preferably a group represented by CR^(Z1) wherein R^(Z1) is ahydrogen atom, a halogen atom, an optionally substituted C₁₋₆ alkylgroup, an optionally substituted C₂₋₆ alkenyl group, an optionallysubstituted C₁₋₆ alkoxy group or a cyano group.

In another embodiment, Z¹ is preferably a group represented by CR^(Z1)wherein R^(Z1) is a hydrogen atom, a halogen atom, an optionallysubstituted C₁₋₆ alkyl group, an optionally substituted C₂₋₆ alkenylgroup, an optionally substituted C₁₋₆ alkoxy group, a cyano group or anoptionally substituted cyclic group, more preferably a group representedby CR^(Z1) wherein R^(Z1) is a hydrogen atom, a halogen atom, anoptionally substituted C₁₋₆ alkyl group, an optionally substituted C₂₋₆alkenyl group, an optionally substituted C₁₋₆ alkoxy group, a cyanogroup, an optionally substituted C₆₋₁₄ aryl group, an optionallysubstituted heterocyclic group or an optionally substituted C₃₋₈cycloalkyl group.

Z¹ is more preferably

-   a group represented by CR^(Z1) wherein R^(Z1) is-   (1) a hydrogen atom,-   (2) a halogen atom (e.g., a chlorine atom),-   (3) a C₁₋₆ alkyl group (e.g., methyl, ethyl) optionally substituted    by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₆₋₁₄ aryl (e.g., phenyl),-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),-   (5) a C₁₋₆ alkoxy group (e.g., methoxy), or-   (6) a cyano group.

In another embodiment, Z¹ is more preferably

-   a group represented by CR^(Z1) wherein R^(Z1) is-   (1) a hydrogen atom,-   (2) a halogen atom (e.g., a chlorine atom),-   (3) a C₁₋₆ alkyl group (e.g., methyl, ethyl) optionally substituted    by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₆₋₁₄ aryl (e.g., phenyl),-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),-   (5) a C₁₋₆ alkoxy group (e.g., methoxy),-   (6) a cyano group,-   (7) a C₆₋₁₄ aryl group (e.g., phenyl) optionally substituted by 1 to    3 C₁₋₆ alkoxy (e.g., methoxy),-   (8) a heterocyclic group (preferably a 5- or 6-membered heterocyclic    group) (e.g., pyrazolyl, thienyl, furyl, isoxazolyl, pyridyl,    dihydropyranyl, tetrahydropyranyl, tetrahydropyridyl, piperidyl)    optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl), or-   (9) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl).

Z¹ is still more preferably

-   a group represented by CR^(Z1) wherein R^(Z1) is a hydrogen atom.

Z² is a group represented by CR^(Z2) wherein R^(Z2) is a hydrogen atom,a halogen atom, an optionally substituted C₁₋₆ alkyl group, anoptionally substituted C₂₋₆ alkenyl group, an optionally substitutedC₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, anoptionally substituted amino group, a cyano group or an optionallysubstituted cyclic group, or a nitrogen atom.

Z² is preferably a group represented by CR^(Z2) wherein R^(Z2) is ahydrogen atom, a halogen atom, an optionally substituted C₁₋₆ alkylgroup, an optionally substituted C₂₋₆ alkenyl group, a cyano group or anoptionally substituted cyclic group.

Z² is more preferably a group represented by CR^(Z2) wherein R^(Z2) is ahydrogen atom, a halogen atom, an optionally substituted C₁₋₆ alkylgroup, a cyano group, an optionally substituted C₆₋₁₄ aryl group or anoptionally substituted C₃₋₈ cycloalkyl group.

Z² is particularly preferably

-   a group represented by CR^(Z2) wherein R^(Z2) is-   (1) a hydrogen atom,-   (2) a halogen atom (e.g., a bromine atom, an iodine atom),-   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, ethyl,    isopropyl) (preferably optionally substituted by 1 to 3 halogen    atoms (e.g., a fluorine atom)),-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),-   (5) a cyano group,-   (6) a C₆₋₁₄ aryl group (e.g., phenyl), or-   (7) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl).

Z² is preferably a group represented by CR^(Z2) wherein R^(Z2) is ahydrogen atom, a halogen atom, an optionally substituted C₁₋₆ alkylgroup, an optionally substituted C₂₋₆ alkenyl group, an optionallysubstituted C₁₋₆ alkoxy group, a cyano group or an optionallysubstituted cyclic group.

In another embodiment, Z² is preferably a group represented by CR^(Z2)wherein R^(Z2) is a hydrogen atom, a halogen atom, an optionallysubstituted C₁₋₆ alkyl group, an optionally substituted C₂₋₆ alkenylgroup, an optionally substituted C₁₋₆ alkoxy group, a cyano group or anoptionally substituted cyclic group, or a nitrogen atom.

Z² is more preferably a group represented by CR^(Z2) wherein R^(Z2) is ahydrogen atom, a halogen atom, an optionally substituted C₁₋₆ alkylgroup, an optionally substituted C₁₋₆ alkoxy group, a cyano group, anoptionally substituted C₆₋₁₄ aryl group or an optionally substitutedC₃₋₈ cycloalkyl group.

In another embodiment, Z² is more preferably a group represented byCR^(Z2) wherein R^(Z2) is a hydrogen atom, a halogen atom, an optionallysubstituted C₁₋₆ alkyl group, an optionally substituted C₂₋₆ alkenylgroup, an optionally substituted C₁₋₆ alkoxy group, a cyano group, anoptionally substituted C₆₋₁₄ aryl group, an optionally substitutedheterocyclic group or an optionally substituted C₃₋₈ cycloalkyl group,or a nitrogen atom.

Z² is particularly preferably

-   a group represented by CR^(Z2) wherein R^(Z2) is-   (1) a hydrogen atom,-   (2) a halogen atom (e.g., a bromine atom, an iodine atom),-   (3) optionally halogenated C₁₋₆ alkyl group (e.g., methyl, ethyl,    isopropyl) (preferably optionally substituted by 1 to 3 halogen    atoms (e.g., a fluorine atom)),-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),-   (5) a C₁₋₆ alkoxy group (e.g., methoxy),-   (6) a cyano group,-   (7) a C₆₋₁₄ aryl group (e.g., phenyl), or-   (8) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl).

In another embodiment, Z² is particularly preferably a group representedby CR^(Z2) wherein R^(Z2) is

-   (1) a hydrogen atom,-   (2) a halogen atom (e.g., a fluorine atom, a chlorine atom, a    bromine atom, an iodine atom),-   (3) a C₁₋₆ alkyl group (e.g., methyl, ethyl, isopropyl) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) hydroxy,-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),-   (5) an optionally halogenated C₁₋₆ alkoxy group (e.g., methoxy,    ethoxy, isopropoxy) (preferably optionally substituted by 1 to 3    halogen atoms (e.g., a fluorine atom)),-   (6) a cyano group,-   (7) a C₆₋₁₄ aryl group (e.g., phenyl),-   (8) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl), or-   (9) a heterocyclic group (e.g., azetidinyl, pyrazolyl) optionally    substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl), or a nitrogen atom.

Z² is most preferably a group represented by CR^(Z2) wherein R^(Z2) is

-   (1) a C₁₋₆ alkoxy group (e.g., methoxy), or-   (2) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl).

In another embodiment, Z² is most preferably a group represented byCR^(Z2) wherein R^(Z2) is an optionally substituted C₁₋₆ alkoxy group,an optionally substituted C₁₋₆ alkyl group or an optionally substitutedC₃₋₈ cycloalkyl group.

In another embodiment, Z² is most preferably a group represented byCR^(Z2) wherein R^(Z2) is

-   (1) a C₁₋₆ alkoxy group (e.g., methoxy),-   (2) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl), or-   (3) a C₁₋₆ alkyl group (e.g., methyl).

Z³ is a group represented by CR^(Z3) wherein R^(Z3) is a hydrogen atom,a halogen atom, an optionally substituted C₁₋₆ alkyl group, anoptionally substituted C₂₋₆ alkenyl group, an optionally substitutedC₂₋₆ alkynyl group, an optionally substituted C₁₋₆ alkoxy group, anoptionally substituted amino group, a cyano group or an optionallysubstituted cyclic group, or a nitrogen atom.

In another embodiment, Z³ is a group represented by CR^(Z3) whereinR^(Z3) is a hydrogen atom, a halogen atom, an optionally substitutedC₁₋₆ alkyl group, an optionally substituted C₂₋₆ alkenyl group, anoptionally substituted C₂₋₆ alkynyl group, an optionally substitutedC₁₋₆ alkoxy group, an optionally substituted amino group, a cyano group,an optionally substituted C₁₋₆ alkyl-carbonyl group or an optionallysubstituted cyclic group, or a nitrogen atom.

Z³ is preferably a group represented by CR^(Z3) wherein R^(Z3) is ahydrogen atom or an optionally substituted C₁₋₆ alkyl group, or anitrogen atom.

In another embodiment, Z³ is preferably a group represented by CR^(Z3)wherein R^(Z3) is a hydrogen atom, an optionally substituted C₁₋₆ alkylgroup, an optionally substituted C₁₋₆ alkoxy group or an optionallysubstituted C₁₋₆ alkyl-carbonyl group, or a nitrogen atom.

Z³ is more preferably a group represented by CR^(Z3) wherein R^(Z3) is ahydrogen atom or a C₁₋₆ alkyl group (e.g., methyl), or a nitrogen atom.

In another embodiment, Z³ is more preferably

-   a group represented by CR^(Z3) wherein R^(Z3) is-   (1) a hydrogen atom,-   (2) a C₁₋₆ alkyl group (e.g., methyl, isopropyl) optionally    substituted by 1 to 3 hydroxy groups,-   (3) a C₁₋₆ alkoxy group (e.g., methoxy), or-   (4) a C₁₋₆ alkyl-carbonyl group (e.g., acetyl),    or a nitrogen atom.

Z³ is still more preferably a group represented by CR^(Z3) whereinR^(Z3) is a hydrogen atom.

B is a nitrogen-containing aromatic heterocycle containing 1 or 2nitrogen atoms.

B is preferably a 6-membered nitrogen-containing aromatic heterocyclecontaining 1 or 2 nitrogen atoms.

B is more preferably a pyridine ring or a pyrazine ring.

In another embodiment, B is more preferably a pyridine ring, apyrimidine ring or a pyrazine ring.

B is particularly preferably a pyridine ring.

Preferable examples of compound (1) include the following compounds.

[Compound A-1]

compound (1) wherein

-   R^(l) is a hydrogen atom or an optionally substituted C₁₋₆ alkyl    group;-   R² and R³ are each a hydrogen atom or an optionally substituted C₁₋₆    alkyl group;-   X is an optionally substituted C₁₋₆ alkylene group (preferably an    optionally substituted C₁₋₅ alkylene group);-   A is a C₆₋₁₀ aryl group or a 5- or 6-membered nitrogen-containing    aromatic heterocyclic group, each of which is optionally    substituted;-   Z¹ is a group represented by CR^(Z1) wherein R^(Zl) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₁₋₆ alkoxy group or a cyano group;-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, a cyano group, an    optionally substituted C₆₋₁₄ aryl group or an optionally substituted    C₃₋₈ cycloalkyl group;-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is a hydrogen    atom or an optionally substituted C₁₋₆ alkyl group, or a nitrogen    atom; and-   B is a 6-membered nitrogen-containing aromatic heterocycle    containing 1 or 2 nitrogen atoms.    [Compound A-2]    compound (1) wherein-   R^(l) is a hydrogen atom or an optionally substituted C₁₋₆ alkyl    group;-   R² and R³ are each a hydrogen atom or an optionally substituted C₁₋₆    alkyl group;-   X is an optionally substituted C₁₋₆ alkylene group (preferably an    optionally substituted C₁₋₅ alkylene group);-   A is a C₆₋₁₀ aryl group or a 5- or 6-membered nitrogen-containing    aromatic heterocyclic group, each of which is optionally    substituted;-   Z¹ is a group represented by CR^(Z1) wherein R^(Zl) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₁₋₆ alkoxy group or a cyano group;-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₁₋₆ alkoxy group, a cyano group, an optionally substituted C₆₋₁₄    aryl group or an optionally substituted C₃₋₈ cycloalkyl group;-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is a hydrogen    atom or an optionally substituted C₁₋₆ alkyl group, or a nitrogen    atom; and-   B is a 6-membered nitrogen-containing aromatic heterocycle    containing 1 or 2 nitrogen atoms.    [Compound A-3]    compound (1) wherein-   R^(l) is a hydrogen atom or an optionally substituted C₁₋₆ alkyl    group;-   R² and R³ are each a hydrogen atom or an optionally substituted C₁₋₆    alkyl group;-   X is an optionally substituted C₁₋₆ alkylene group (preferably an    optionally substituted C₁₋₅ alkylene group);-   A is a C₆₋₁₀ aryl group, a 4- to 10-membered heterocyclic group or a    C₃₋₈ cycloalkyl group, each of which is optionally substituted;-   Z¹ is a group represented by CR^(Z1) wherein R^(Zl) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₁₋₆ alkoxy group or a cyano group;-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is a hydrogen    atom, a halogen atom, an optionally substituted C₁₋₆ alkyl group, an    optionally substituted C₂₋₆ alkenyl group, an optionally substituted    C₁₋₆ alkoxy group, a cyano group, an optionally substituted C₆₋₁₄    aryl group or an optionally substituted C₃₋₈ cycloalkyl group, or a    nitrogen atom;-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is a hydrogen    atom or an optionally substituted C₁₋₆ alkyl group, or a nitrogen    atom; and-   B is a 6-membered nitrogen-containing aromatic heterocycle    containing 1 or 2 nitrogen atoms.    [Compound A-4]    compound (1) wherein-   R¹ is a hydrogen atom,-   R² and R³ are both hydrogen atoms,-   X is an optionally substituted C₁₋₆ alkylene group,-   A is an optionally substituted phenyl group,-   Z¹ is CH,-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is an optionally    substituted C₁₋₆ alkyl group, an optionally substituted C₁₋₆ alkoxy    group or an optionally substituted C₃₋₈ cycloalkyl group, and-   Z³ is CH.    [Compound B-1]    compound (1) wherein-   R¹ is a hydrogen atom or a C₁₋₆ alkyl group;-   R² and R³ are both hydrogen atoms;-   X is a C₁₋₆ alkylene group (preferably a C₁₋₅ alkylene group, more    preferably —CH₂—, —CH(CH₃)—, —CH(CH₂CH₃)—, —CH(CH₂CH₂CH₃)— or    —CH(CH(CH₃)₂)—) optionally substituted by 1 to 3 substituents    selected from-   (1) hydroxy,-   (2) cyano,-   (3) carbamoyl,-   (4) C₁₋₆ alkoxy (e.g., methoxy),-   (5) C₁₋₆ alkylsulfanyl (e.g., methylsulfanyl),-   (6) C₁₋₆ alkylsulfonyl (e.g., methylsulfonyl),-   (7) mono- or di-C₁₋₆ alkyl-amino (e.g., dimethylamino),-   (8) C₃₋₈ cycloalkyl (e.g., cyclopropyl),-   (9) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by 1 to 3    substituents selected from optionally halogenated C₁₋₆ alkoxy (e.g.,    methoxy) (preferably optionally substituted by 1 to 3 halogen atoms    (e.g., a fluorine atom)), and-   (10) a heterocyclic group (preferably a 5- or 6-membered aromatic    heterocyclic group) (e.g., pyridyl, isoxazolyl, pyrazolyl)    optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl);-   A is a C₆₋₁₀ aryl group or a 5- or 6-membered aromatic heterocyclic    group (preferably a C₆₋₁₀ aryl group or a 5- or 6-membered    nitrogen-containing aromatic heterocyclic group, more preferably    phenyl, pyridazinyl, pyridyl, pyrimidinyl, isoxazolyl or pyrazolyl,    particularly preferably phenyl), each of which is optionally    substituted by 1 to 3 substituents selected from-   (1) a halogen atom (e.g., a fluorine atom),-   (2) hydroxy,-   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, isopropyl)    (preferably optionally substituted by 1 to 3 halogen atoms (e.g., a    fluorine atom)),-   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),-   (5) C₁₋₆ alkoxy (e.g., methoxy) optionally substituted by 1 to 3    substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),-   (6) C₆₋₁₄ aryl (e.g., phenyl), and-   (7) a heterocyclic group (preferably a 5- or 6-membered heterocyclic    group) (e.g., pyrazolyl, dihydropyranyl, tetrahydropyranyl)    optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl);    [preferably the group represented by

is a group represented by

-   -   wherein    -   R²¹ is a hydrogen atom, an optionally substituted C₁₋₅ alkyl        group, a C₃₋₈ cycloalkyl group, a carbamoyl group or a cyano        group, and    -   R²² is a hydrogen atom or a substituent]

-   Z¹ is a group represented by CR^(Z1) wherein R^(Z1) is

-   (1) a hydrogen atom,

-   (2) a halogen atom (e.g., a chlorine atom),

-   (3) a C₁₋₆ alkyl group (e.g., methyl, ethyl) optionally substituted    by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) a C₆₋₁₄ aryl group (e.g., phenyl),

-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),

-   (5) a C₁₋₆ alkoxy group (e.g., methoxy), or

-   (6) a cyano group;

-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is

-   (1) a hydrogen atom,

-   (2) a halogen atom (e.g., a bromine atom, an iodine atom),

-   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, ethyl,    isopropyl) (preferably optionally substituted by 1 to 3 halogen    atoms (e.g., a fluorine atom)),

-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),

-   (5) a cyano group,

-   (6) a C₆₋₁₄ aryl group (e.g., phenyl), or

-   (7) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl);

-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is a hydrogen    atom or a C₁₋₆ alkyl group, or a nitrogen atom; and

-   B is a pyridine ring or a pyrazine ring.    [Compound B-2]    compound (1) wherein

-   R¹ is a hydrogen atom or a C₁₋₆ alkyl group (preferably methyl);

-   R² and R³ are both hydrogen atoms;

-   X is a C₁₋₆ alkylene group (preferably a C₁₋₅ alkylene group, more    preferably —CH₂—, —CH(CH₃)—, —CH(CH₂CH₃)—, —CH(CH₂CH₂CH₃)— or    —CH(CH(CH₃)₂)—) optionally substituted by 1 to 3 substituents    selected from

-   (1) hydroxy,

-   (2) cyano,

-   (3) carbamoyl,

-   (4) C₁₋₆ alkoxy (e.g., methoxy),

-   (5) C₁₋₆ alkylsulfanyl (e.g., methylsulfanyl),

-   (6) C₁₋₆ alkylsulfonyl (e.g., methylsulfonyl),

-   (7) mono- or di-C₁₋₆ alkyl-amino (e.g., dimethylamino),

-   (8) C₃₋₈ cycloalkyl (e.g., cyclopropyl),

-   (9) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by 1 to 3    substituents selected from optionally halogenated C₁₋₆ alkoxy (e.g.,    methoxy) (preferably optionally substituted by 1 to 3 halogen atoms    (e.g., a fluorine atom)), and

-   (10) a heterocyclic group (preferably a 5- or 6-membered aromatic    heterocyclic group) (e.g., pyridyl, isoxazolyl, pyrazolyl)    optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl);

-   A is a C₆₋₁₀ aryl group or a 5- or 6-membered aromatic heterocyclic    group (preferably a C₆₋₁₀ aryl group or a 5- or 6-membered    nitrogen-containing aromatic heterocyclic group, more preferably    phenyl, pyridazinyl, pyridyl, pyrimidinyl, isoxazolyl or pyrazolyl,    particularly preferably phenyl), each of which is optionally    substituted by 1 to 3 substituents selected from

-   (1) a halogen atom (e.g., a fluorine atom),

-   (2) hydroxy,

-   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, isopropyl)    (preferably optionally substituted by 1 to 3 halogen atoms (e.g., a    fluorine atom)),

-   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),

-   (5) C₁₋₆ alkoxy (e.g., methoxy) optionally substituted by 1 to 3    substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),

-   (6) C₆₋₁₄ aryl (e.g., phenyl), and

-   (7) a heterocyclic group (preferably a 5- or 6-membered heterocyclic    group) (e.g., pyrazolyl, dihydropyranyl, tetrahydropyranyl)    optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl);    [preferably the group represented by

is a group represented by

-   -   wherein    -   R²¹ is    -   (1) cyano,    -   (2) carbamoyl,    -   (3) C₁₋₅ alkyl (e.g., methyl, ethyl, isopropyl, propyl)        optionally substituted by 1 to 3 substituents selected from        -   (i) hydroxy,        -   (ii) C₁₋₆ alkoxy (e.g., methoxy),        -   (iii) mono- or di-C₁₋₆ alkyl-amino (e.g., dimethylamino),        -   (iv) C₁₋₆ alkylsulfanyl (e.g., methylsulfanyl), and        -   (v) C₁₋₆ alkylsulfonyl (e.g., methylsulfonyl),    -   (4) C₃₋₈ cycloalkyl (e.g., cyclopropyl), or    -   (5) a heterocyclic group (preferably a 5- or 6-membered aromatic        heterocyclic group) (e.g., pyridyl, isoxazolyl, pyrazolyl)        optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl),    -   R²² is    -   (1) a halogen atom (e.g., a fluorine atom),    -   (2) hydroxy,    -   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, isopropyl)        (preferably optionally substituted by 1 to 3 halogen atoms        (e.g., a fluorine atom)),    -   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),    -   (5) C₁₋₆ alkoxy (e.g., methoxy) optionally substituted by 1 to 3        substituents selected from        -   (i) a halogen atom (e.g., a fluorine atom), and        -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),    -   (6) C₆₋₁₄ aryl (e.g., phenyl), or    -   (7) a heterocyclic group (preferably a 5- or 6-membered        heterocyclic group) (e.g., pyrazolyl, dihydropyranyl,        tetrahydropyranyl) optionally substituted by 1 to 3 C₁₋₆ alkyl        (e.g., methyl), and    -   p is an integer of 1 to 3],

-   Z¹ is a group represented by CR^(Z1) wherein R^(Z1) is

-   (1) a hydrogen atom,

-   (2) a halogen atom (e.g., a chlorine atom),

-   (3) a C₁₋₆ alkyl group (e.g., methyl, ethyl) optionally substituted    by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₆₋₁₄ aryl (e.g., phenyl),

-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),

-   (5) a C₁₋₆ alkoxy group (e.g., methoxy), or

-   (6) a cyano group;

-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is

-   (1) a hydrogen atom,

-   (2) a halogen atom (e.g., a bromine atom, an iodine atom),

-   (3) an optionally halogenated C₁₋₆ alkyl group (e.g., methyl, ethyl,    isopropyl) (preferably optionally substituted by 1 to 3 halogen    atoms (e.g., a fluorine atom)),

-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),

-   (5) a C₁₋₆ alkoxy group (e.g., methoxy),

-   (6) a cyano group,

-   (7) a C₆₋₁₄ aryl group (e.g., phenyl), or

-   (8) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl);

-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is a hydrogen    atom or a C₁₋₆ alkyl group (e.g., methyl), or a nitrogen atom; and

-   B is a pyridine ring or a pyrazine ring.    [Compound B-3]    compound (1) wherein

-   R¹ is a hydrogen atom or a C₁₋₆ alkyl group (preferably methyl);

-   R² and R³ are each independently a hydrogen atom or a C₁₋₆ alkyl    group (preferably methyl);

-   X is a C₁₋₆ alkylene group (preferably C₁₋₆ alkylene group, more    preferably —CH₂—, —CH(CH₃)—, —CH(CH₂CH₃)—, —CH(CH₂CH₂CH₃)—,    —CH(CH(CH₃)₂)—, —CH(C(CH₃)₃)—, —CH(CH₂CH₂CH₂CH₃)—, —CH(CH(CH₂CH₃)₂)—    or —CH₂CH₂—) optionally substituted by 1 to 5 substituents selected    from

-   (1) a halogen atom (e.g., a fluorine atom),

-   (2) hydroxy,

-   (3) amino,

-   (4) cyano,

-   (5) carbamoyl,

-   (6) mono- or di-C₁₋₆ alkyl-carbamoyl (e.g., methylcarbamoyl,    dimethylcarbamoyl),

-   (7) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₁₋₆ alkoxy (e.g., methoxy),

-   (8) C₁₋₆ alkylsulfanyl (e.g., methylsulfanyl),

-   (9) C₁₋₆ alkylsulfinyl (e.g., methylsulfinyl),

-   (10) C₁₋₆ alkylsulfonyl (e.g., methylsulfonyl),

-   (11) mono- or di-C₁₋₆ alkyl-amino (e.g., dimethylamino),

-   (12) C₃₋₈ cycloalkyl (e.g., cyclopropyl),

-   (13) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by 1 to 3    substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom, a bromine atom),    -   (ii) hydroxy, and    -   (iii) optionally halogenated C₁₋₆ alkoxy (e.g., methoxy)        (preferably optionally substituted by 1 to 3 halogen atoms        (e.g., a fluorine atom)),

-   (14) a heterocyclic group (preferably a 4- to 10-membered    heterocyclic group) (e.g., pyridyl, isoxazolyl, pyrazolyl,    pyrrolidinyl, triazolyl, oxetanyl, tetrahydrofuryl,    tetrahydropyranyl, dihydroisoindolyl) optionally substituted by 1 to    3 substituents selected from    -   (i) C₁₋₆ alkyl (e.g., methyl),    -   (ii) hydroxy, and    -   (iii) oxo,

-   (15) C₃₋₈ cycloalkyloxy (e.g., cyclopentyloxy),

-   (16) optionally halogenated heterocyclyl-oxy (e.g., pyridyloxy)    (preferably optionally substituted by 1 to 3 halogen atoms (e.g., a    bromine atom)),

-   (17) C₁₋₆ alkyl-carbonyloxy (e.g., acetoxy),

-   (18) C₁₋₆ alkyl(diaryl)silyloxy (e.g., tert-butyl(diphenyl)    silyloxy),

-   (19) C₁₋₆ alkyl-carbonyl (e.g., acetyl), and

-   (20) C₃₋₈ cycloalkyl-carbonyl (e.g., cyclopropylcarbonyl), or a    bond;

-   A is a C₆₋₁₀ aryl group, a 4- to 10-membered heterocyclic group or a    C₃₋₈ cycloalkyl group (preferably phenyl, pyridazinyl, pyridyl,    pyrimidinyl, isoxazolyl, pyrazolyl, oxetanyl, pyrrolidinyl,    tetrahydrofuryl, imidazolyl, triazolyl, thienyl, tetrahydropyranyl,    imidazo[1,2-a]pyridyl, benzodioxolyl, pyrazolo[1,5-a]pyridyl,    dihydroisoindolyl or cyclopropyl, more preferably phenyl), each of    which is optionally substituted by 1 to 3 substituents selected from

-   (1) a halogen atom (e.g., a fluorine atom, a chlorine atom, a    bromine atom),

-   (2) hydroxy,

-   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, ethyl,    isopropyl) (e.g., a fluorine atom)) (preferably optionally    substituted by 1 to 3 halogen atoms,

-   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),

-   (5) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),

-   (6) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by optionally    halogenated C₁₋₆ alkoxy (e.g., methoxy) (preferably optionally    substituted by 1 to 3 halogen atoms (e.g., a fluorine atom)),

-   (7) a heterocyclic group (preferably a 4- to 6-membered heterocyclic    group) (e.g., azetidinyl, pyrazolyl, pyrrolyl, pyrrolidinyl,    triazolyl, dihydropyranyl, tetrahydropyranyl) optionally substituted    by 1 to 3 C₁₋₆ alkyl (e.g., methyl),

-   (8) C₃₋₈ cycloalkyl (e.g., cyclopropyl), and

-   (9) oxo;    [preferably the group represented by

is a group represented by

-   -   wherein    -   R²¹ is    -   (1) cyano,    -   (2) carbamoyl,    -   (3) mono- or di-C₁₋₆ alkyl-carbamoyl (e.g., methylcarbamoyl,        dimethylcarbamoyl),    -   (4) C₁₋₆ alkyl (e.g., methyl, ethyl, isopropyl, propyl, butyl,        tert-butyl, l-ethylpropyl) optionally substituted by 1 to 5        substituents selected from        -   (i) a halogen atom (e.g., a fluorine atom),        -   (ii) hydroxy,        -   (iii) amino,        -   (iv) cyano,        -   (v) C₃₋₈ cycloalkyl (e.g., cyclopropyl),        -   (vi) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy)            optionally substituted by 1 to 3 substituents selected from            -   (a) a halogen atom (e.g., a fluorine atom), and            -   (b) C₁₋₆ alkoxy (e.g., methoxy),        -   (vii) C₃₋₈ cycloalkyloxy (e.g., cyclopentyloxy),        -   (viii) mono- or di-C₁₋₆ alkyl-amino (e.g., dimethylamino),        -   (ix) C₁₋₆ alkylsulfanyl (e.g., methylsulfanyl),        -   (x) C₁₋₆ alkylsulfinyl (e.g., methylsulfinyl),        -   (xi) C₁₋₆ alkylsulfonyl (e.g., methylsulfonyl),        -   (xii) carbamoyl,        -   (xiii) mono- or di-C₁₋₆ alkyl-carbamoyl (e.g.,            dimethylcarbamoyl),        -   (xiv) a heterocyclic group (e.g., oxetanyl, pyrrolidinyl,            pyrazolyl, triazolyl, tetrahydropyranyl, dihydroisoindolyl)            optionally substituted by 1 to 3 substituents selected from            -   (a) hydroxy, and            -   (b) oxo,        -   (xv) C₁₋₆ alkyl-carbonyloxy (e.g., acetoxy),        -   (xvi) C₁₋₆ alkyl(diaryl)silyloxy (e.g.,            tert-butyl(diphenyl)silyloxy), and        -   (xvii) optionally halogenated heterocyclyl-oxy (e.g.,            pyridyloxy) (preferably optionally substituted by 1 to 3            halogen atoms (e.g., a bromine atom)),    -   (5) C₃₋₈ cycloalkyl (e.g., cyclopropyl),    -   (6) a heterocyclic group (preferably a 4- to 6-membered        heterocyclic group) (e.g., pyridyl, isoxazolyl, pyrazolyl,        oxetanyl, tetrahydrofuryl, tetrahydropyranyl) optionally        substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl),    -   (7) C₁₋₆ alkyl-carbonyl (e.g., acetyl),    -   (8) C₃₋₈ cycloalkyl-carbonyl (e.g., cyclopropylcarbonyl), or    -   (9) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by 1 to 3        substituents selected from        -   (i) a halogen atom (e.g., a fluorine atom, a bromine atom),        -   (ii) hydroxy,        -   (iii) optionally halogenated C₁₋₆ alkoxy (e.g., methoxy)            (preferably optionally substituted by 1 to 3 halogen atoms            (e.g., a fluorine atom)),    -   R²² is    -   (1) a halogen atom (e.g., a fluorine atom, a chlorine atom, a        bromine atom),    -   (2) hydroxy,    -   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, isopropyl)        (preferably optionally substituted by 1 to 3 halogen atoms        (e.g., a fluorine atom)),    -   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),    -   (5) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally        substituted by 1 to 3 substituents selected from        -   (i) a halogen atom (e.g., a fluorine atom), and        -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),    -   (6) C₆₋₁₄ aryl (e.g., phenyl),    -   (7) a heterocyclic group (preferably a 4- to 6-membered        heterocyclic group) (e.g., azetidinyl, pyrazolyl, pyrrolyl,        pyrrolidinyl, triazolyl, dihydropyranyl, tetrahydropyranyl)        optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl), or    -   (8) C₃₋₈ cycloalkyl (e.g., cyclopropyl), and    -   p is an integer of 1 to 3],

-   Z¹ is a group represented by CR^(Z1) wherein R^(Z1) is

-   (1) a hydrogen atom,

-   (2) a halogen atom (e.g., a chlorine atom),

-   (3) a C₁₋₆ alkyl group (e.g., methyl, ethyl) optionally substituted    by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₆₋₁₄ aryl (e.g., phenyl),

-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),

-   (5) a C₁₋₆ alkoxy group (e.g., methoxy),

-   (6) a cyano group,

-   (7) a C₆₋₁₄ aryl group (e.g., phenyl) optionally substituted by 1 to    3 C₁₋₆ alkoxy (e.g., methoxy),

-   (8) a heterocyclic group (preferably a 5- or 6-membered heterocyclic    group) (e.g., pyrazolyl, thienyl, furyl, isoxazolyl, pyridyl,    dihydropyranyl, tetrahydropyranyl, tetrahydropyridyl, piperidyl)    optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl), or

-   (9) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl);

-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is

-   (1) a hydrogen atom,

-   (2) a halogen atom (e.g., a fluorine atom, a chlorine atom, a    bromine atom, an iodine atom),

-   (3) C₁₋₆ alkyl (e.g., methyl, ethyl, isopropyl) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) hydroxy,

-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),

-   (5) an optionally halogenated C₁₋₆ alkoxy group (e.g., methoxy,    ethoxy, isopropoxy) (preferably optionally substituted by 1 to 3    halogen atoms (e.g., a fluorine atom)),

-   (6) a cyano group,

-   (7) a C₆₋₁₄ aryl group (e.g., phenyl),

-   (8) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl), or

-   (9) a heterocyclic group (e.g., azetidinyl, pyrazolyl) optionally    substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl), or a nitrogen atom;

-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is

-   (1) a hydrogen atom,

-   (2) a C₁₋₆ alkyl group (e.g., methyl, isopropyl) optionally    substituted by 1 to 3 hydroxy,

-   (3) a C₁₋₆ alkoxy group (e.g., methoxy), or

-   (4) a C₁₋₆ alkyl-carbonyl group (e.g., acetyl), or a nitrogen atom;    and

-   B is a pyridine ring, a pyrimidine ring or a pyrazine ring.    [Compound B-4]    compound (1) wherein

-   R¹ is a hydrogen atom or a C₁₋₆ alkyl group (preferably methyl);

-   R² and R³ are each independently a hydrogen atom or a C₁₋₆ alkyl    group (preferably methyl);

-   X is a C₁₋₆ alkylene group (preferably —CH₂—, —CH(CH₃)—,    —CH(CH₂CH₃)—, —CH(CH₂CH₂CH₃)—, —CH(CH(CH₃)₂)—, —CH(C(CH₃)₃)—,    —CH(CH₂CH₂CH₂CH₃)—, —CH(CH(CH₂CH₃)₂)— or —CH₂CH₂—) optionally    substituted by 1 to 5 substituents selected from

-   (1) a halogen atom (e.g., a fluorine atom),

-   (2) hydroxy,

-   (3) amino,

-   (4) cyano,

-   (5) carbamoyl,

-   (6) mono- or di-C₁₋₆ alkyl-carbamoyl (e.g., methylcarbamoyl,    dimethylcarbamoyl),

-   (7) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₁₋₆ alkoxy (e.g., methoxy),

-   (8) C₁₋₆ alkylsulfanyl (e.g., methylsulfanyl),

-   (9) C₁₋₆ alkylsulfinyl (e.g., methylsulfinyl),

-   (10) C₁₋₆ alkylsulfonyl (e.g., methylsulfonyl),

-   (11) mono- or di-C₁₋₆ alkyl-amino (e.g., dimethylamino),

-   (12) C₃₋₈ cycloalkyl (e.g., cyclopropyl),

-   (13) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by 1 to 3    substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom, a bromine atom),    -   (ii) hydroxy, and    -   (iii) optionally halogenated C₁₋₆ alkoxy (e.g., methoxy)        (preferably optionally substituted by 1 to 3 halogen atoms        (e.g., a fluorine atom)),

-   (14) a heterocyclic group (preferably a 4- to 10-membered    heterocyclic group) (e.g., pyridyl, isoxazolyl, pyrazolyl,    pyrrolidinyl, triazolyl, oxetanyl, tetrahydrofuryl,    tetrahydropyranyl, dihydroisoindolyl) optionally substituted by 1 to    3 substituents selected from    -   (i) C₁₋₆ alkyl (e.g., methyl),    -   (ii) hydroxy, and    -   (iii) oxo,

-   (15) C₃₋₈ cycloalkyloxy (e.g., cyclopentyloxy),

-   (16) optionally halogenated heterocyclyl-oxy (e.g., pyridyloxy)    (preferably optionally substituted by 1 to 3 halogen atoms (e.g., a    bromine atom)),

-   (17) C₁₋₆ alkyl-carbonyloxy (e.g., acetoxy),

-   (18) C₁₋₆ alkyl(diaryl)silyloxy (e.g., tert-butyl(diphenyl)    silyloxy),

-   (19) C₁₋₆ alkyl-carbonyl (e.g., acetyl), and

-   (20) C₃₋₈ cycloalkyl-carbonyl (e.g., cyclopropylcarbonyl), or a    bond;

-   A is a C₆₋₁₀ aryl group, a 4- to 10-membered heterocyclic group or a    C₃₋₈ cycloalkyl group (preferably phenyl, pyridazinyl, pyridyl,    pyrimidinyl, isoxazolyl, pyrazolyl, oxetanyl, pyrrolidinyl,    tetrahydrofuryl, imidazolyl, triazolyl, thienyl, tetrahydropyranyl,    imidazo[1,2-a]pyridyl, benzodioxolyl, pyrazolo[1,5-a]pyridyl,    dihydroisoindolyl or cyclopropyl, more preferably phenyl), each of    which is optionally substituted by 1 to 3 substituents selected from

-   (1) a halogen atom (e.g., a fluorine atom, a chlorine atom, a    bromine atom),

-   (2) hydroxy,

-   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, ethyl,    isopropyl) (preferably optionally substituted by 1 to 3 halogen    atoms (e.g., a fluorine atom)),

-   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),

-   (5) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),

-   (6) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by optionally    halogenated C₁₋₆ alkoxy (e.g., methoxy) (preferably optionally    substituted by 1 to 3 halogen atoms (e.g., a fluorine atom)),

-   (7) a heterocyclic group (preferably a 4- to 6-membered heterocyclic    group) (e.g., azetidinyl, pyrazolyl, pyrrolyl, pyrrolidinyl,    triazolyl, dihydropyranyl, tetrahydropyranyl) optionally substituted    by 1 to 3 C₁₋₆ alkyl (e.g., methyl),

-   (8) C₃₋₈ cycloalkyl (e.g., cyclopropyl), and

-   (9) oxo;

-   Z¹ is a group represented by CR^(Z1) wherein R^(Z1) is

-   (1) a hydrogen atom,

-   (2) a halogen atom (e.g., a chlorine atom),

-   (3) a C₁₋₆ alkyl group (e.g., methyl, ethyl) optionally substituted    by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₆₋₁₄ aryl (e.g., phenyl),

-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),

-   (5) a C₁₋₆ alkoxy group (e.g., methoxy),

-   (6) a cyano group,

-   (7) a C₆₋₁₄ aryl group (e.g., phenyl) optionally substituted by 1 to    3 C₁₋₆ alkoxy (e.g., methoxy),

-   (8) a heterocyclic group (preferably a 5- or 6-membered heterocyclic    group) (e.g., pyrazolyl, thienyl, furyl, isoxazolyl, pyridyl,    dihydropyranyl, tetrahydropyranyl, tetrahydropyridyl, piperidyl)    optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl), or

-   (9) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl);

-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is

-   (1) a hydrogen atom,

-   (2) a halogen atom (e.g., a fluorine atom, a chlorine atom, a    bromine atom, an iodine atom),

-   (3) a C₁₋₆ alkyl group (e.g., methyl, ethyl, isopropyl) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) hydroxy,

-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),

-   (5) an optionally halogenated C₁₋₆ alkoxy group (e.g., methoxy,    ethoxy, isopropoxy) (preferably optionally substituted by 1 to 3    halogen atoms (e.g., a fluorine atom)),

-   (6) a cyano group,

-   (7) a C₆₋₁₄ aryl group (e.g., phenyl),

-   (8) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl), or

-   (9) a heterocyclic group (e.g., azetidinyl, pyrazolyl) optionally    substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl), or a nitrogen atom;

-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is

-   (1) a hydrogen atom,

-   (2) a C₁₋₆ alkyl group (e.g., methyl, isopropyl) optionally    substituted by 1 to 3 hydroxy,

-   (3) a C₁₋₆ alkoxy group (e.g., methoxy), or

-   (4) a C₁₋₆ alkyl-carbonyl group (e.g., acetyl), or a nitrogen atom;    and

-   B is a pyridine ring, a pyrimidine ring or a pyrazine ring.    [Compound B-5]    compound (1) wherein

-   R¹ is a hydrogen atom or a C₁₋₆ alkyl group (preferably methyl);

-   R² and R³ are each independently a hydrogen atom or a C₁₋₆ alkyl    group (preferably methyl);    the group represented by

is a group represented by

-   -   wherein    -   R²¹ is    -   (1) cyano,    -   (2) carbamoyl,    -   (3) mono- or di-C₁₋₆ alkyl-carbamoyl (e.g., methylcarbamoyl,        dimethylcarbamoyl),    -   (4) C₁₋₆ alkyl (e.g., methyl, ethyl, isopropyl, propyl, butyl,        tert-butyl, 1-ethylpropyl) optionally substituted by 1 to 5        substituents selected from        -   (i) a halogen atom (e.g., a fluorine atom),        -   (ii) hydroxy,        -   (iii) amino,        -   (iv) cyano,        -   (v) C₃₋₈ cycloalkyl (e.g., cyclopropyl),        -   (vi) C₁₋₈ alkoxy (e.g., methoxy, ethoxy, isopropoxy)            optionally substituted by 1 to 3 substituents selected from            -   (a) a halogen atom (e.g., a fluorine atom), and            -   (b) C₁₋₆ alkoxy (e.g., methoxy),        -   (vii) C₃₋₈ cycloalkyloxy (e.g., cyclopentyloxy),        -   (viii) mono- or di-C₁₋₆ alkyl-amino (e.g., dimethylamino),        -   (ix) C₁₋₆ alkylsulfanyl (e.g., methylsulfanyl),        -   (x) C₁₋₆ alkylsulfinyl (e.g., methylsulfinyl),        -   (xi) C₁₋₆ alkylsulfonyl (e.g., methylsulfonyl),        -   (xii) carbamoyl,        -   (xiii) mono- or di-C₁₋₆ alkyl-carbamoyl (e.g.,            dimethylcarbamoyl),        -   (xiv) a heterocyclic group (e.g., oxetanyl, pyrrolidinyl,            pyrazolyl, triazolyl, tetrahydropyranyl, dihydroisoindolyl)            optionally substituted by 1 to 3 substituents selected from            -   (a) hydroxy, and            -   (b) oxo,        -   (xv) C₁₋₆ alkyl-carbonyloxy (e.g., acetoxy),        -   (xvi) C₁₋₆ alkyl(diaryl)silyloxy (e.g.,            tert-butyl(diphenyl)silyloxy), and        -   (xvii) optionally halogenated heterocyclyl-oxy (e.g.,            pyridyloxy) (preferably optionally substituted by 1 to 3            halogen atoms (e.g., a bromine atom)),    -   (5) C₃₋₈ cycloalkyl (e.g., cyclopropyl),    -   (6) a heterocyclic group (preferably a 4- to 6-membered        heterocyclic group) (e.g., pyridyl, isoxazolyl, pyrazolyl,        oxetanyl, tetrahydrofuryl, tetrahydropyranyl) optionally        substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl),    -   (7) C₁₋₆ alkyl-carbonyl (e.g., acetyl),    -   (8) C₃₋₈ cycloalkyl-carbonyl (e.g., cyclopropylcarbonyl), or    -   (9) C₆₋₁₄ aryl (e.g., phenyl) optionally substituted by 1 to 3        substituents selected from        -   (i) a halogen atom (e.g., a fluorine atom, a bromine atom),            and        -   (ii) hydroxy,    -   R²² is    -   (1) a halogen atom (e.g., a fluorine atom, a chlorine atom, a        bromine atom),    -   (2) hydroxy,    -   (3) optionally halogenated C₁₋₆ alkyl (e.g., methyl, isopropyl)        (preferably optionally substituted by 1 to 3 halogen atoms        (e.g., a fluorine atom)),    -   (4) C₂₋₆ alkenyl (e.g., prop-1-en-2-yl),    -   (5) C₁₋₆ alkoxy (e.g., methoxy, ethoxy, isopropoxy) optionally        substituted by 1 to 3 substituents selected from        -   (i) a halogen atom (e.g., a fluorine atom), and        -   (ii) C₃₋₈ cycloalkyl (e.g., cyclopropyl),    -   (6) C₆₋₁₄ aryl (e.g., phenyl),    -   (7) a heterocyclic group (preferably a 4- to 6-membered        heterocyclic group) (e.g., azetidinyl, pyrazolyl, pyrrolyl,        pyrrolidinyl, triazolyl, dihydropyranyl, tetrahydropyranyl)        optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl), or    -   (8) C₃₋₈ cycloalkyl (e.g., cyclopropyl), and    -   p is an integer of 1 to 3,

-   Z¹ is a group represented by CR^(Z1) wherein R^(Z1) is

-   (1) a hydrogen atom,

-   (2) a halogen atom (e.g., a chlorine atom),

-   (3) a C₁₋₆ alkyl group (e.g., methyl, ethyl) optionally substituted    by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) C₆₋₁₄ aryl (e.g., phenyl),

-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),

-   (5) a C₁₋₆ alkoxy group (e.g., methoxy),

-   (6) a cyano group,

-   (7) a C₆₋₁₄ aryl group (e.g., phenyl) optionally substituted by 1 to    3 C₁₋₆ alkoxy (e.g., methoxy),

-   (8) a heterocyclic group (preferably a 5- or 6-membered heterocyclic    group) (e.g., pyrazolyl, thienyl, furyl, isoxazolyl, pyridyl,    dihydropyranyl, tetrahydropyranyl, tetrahydropyridyl, piperidyl)    optionally substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl), or

-   (9) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl);

-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is

-   (1) a hydrogen atom,

-   (2) a halogen atom (e.g., a fluorine atom, a chlorine atom, a    bromine atom, an iodine atom),

-   (3) a C₁₋₆ alkyl group (e.g., methyl, ethyl, isopropyl) optionally    substituted by 1 to 3 substituents selected from    -   (i) a halogen atom (e.g., a fluorine atom), and    -   (ii) hydroxy,

-   (4) a C₂₋₆ alkenyl group (e.g., vinyl),

-   (5) an optionally halogenated C₁₋₆ alkoxy group (e.g., methoxy,    ethoxy, isopropoxy) (preferably optionally substituted by 1 to 3    halogen atoms (e.g., a fluorine atom)),

-   (6) a cyano group,

-   (7) a C₆₋₁₄ aryl group (e.g., phenyl),

-   (8) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl), or

-   (9) a heterocyclic group (e.g., azetidinyl, pyrazolyl) optionally    substituted by 1 to 3 C₁₋₆ alkyl (e.g., methyl), or a nitrogen atom;

-   Z³ is a group represented by CR^(Z3) wherein R^(Z3) is

-   (1) a hydrogen atom,

-   (2) a C₁₋₆ alkyl group (e.g., methyl, isopropyl) optionally    substituted by 1 to 3 hydroxy,

-   (3) a C₁₋₆ alkoxy group (e.g., methoxy), or

-   (4) a C₁₋₆ alkyl-carbonyl group (e.g., acetyl),

-   or a nitrogen atom; and

-   B is a pyridine ring, a pyrimidine ring or a pyrazine ring.    [Compound C-2]    compound (1) wherein

-   R¹ is a hydrogen atom;

-   R² and R³ are both hydrogen atoms;

-   X is a C₁₋₆ alkylene group (preferably a C₁₋₅ alkylene group, more    preferably —CH(CH₃)— or —CH(CH(CH₃)₂)—) optionally substituted by 1    to 3 substituents selected from

-   (1) hydroxy, and

-   (2) C₁₋₆ alkoxy (e.g., methoxy);

-   A is a C₆₋₁₀ aryl group (e.g., phenyl) optionally substituted by 1    to 3 substituents selected from

-   (1) a halogen atom (e.g., a fluorine atom), and

-   (2) C₁₋₆ alkoxy (e.g., methoxy) optionally substituted by 1 to 3    halogen atoms (e.g., a fluorine atom);    [preferably the group represented by

is a group represented by

-   -   wherein    -   R²¹ is a C₁₋₅ alkyl group (e.g., methyl, isopropyl) optionally        substituted by hydroxy or C₁₋₆ alkoxy (e.g., methoxy),    -   R²² is    -   (1) a halogen atom (e.g., a fluorine atom), or    -   (2) optionally halogenated C₁₋₆ alkoxy (e.g., methoxy)        (preferably optionally substituted by 1 to 3 halogen atoms        (e.g., a fluorine atom)), and    -   p is an integer of 1 or 2];

-   Z¹ is CH;

-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is

-   (1) a C₁₋₆ alkoxy group (e.g., methoxy), or

-   (2) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl);

-   Z³ is CH; and

-   B is a pyridine ring.    [Compound C-3]    compound (1) wherein

-   R¹ is a hydrogen atom;

-   R² and R³ are both hydrogen atoms;

-   X is a C₁₋₆ alkylene group (preferably a C₁₋₅ alkylene group, more    preferably —CH(CH₃)— or —CH(CH(CH₃)₂)—) optionally substituted by 1    to 3 substituents selected from

-   (1) hydroxy, and

-   (2) C₁₋₆ alkoxy (e.g., methoxy);

-   A is a C₆₋₁₀ aryl group (e.g., phenyl) optionally substituted by 1    to 3 substituents selected from

-   (1) a halogen atom (e.g., a fluorine atom), and

-   (2) C₁₋₆ alkoxy (e.g., methoxy) optionally substituted by 1 to 3    halogen atoms (e.g., a fluorine atom);    [preferably the group represented by

is a group represented by

-   -   wherein    -   R²¹ is a C₁₋₅ alkyl group (e.g., methyl, isopropyl) optionally        substituted by hydroxy or C₁₋₆ alkoxy (e.g., methoxy),    -   R²² is    -   (1) a halogen atom (e.g., a fluorine atom), or    -   (2) an optionally halogenated C₁₋₆ alkoxy group (e.g., methoxy)        (preferably optionally substituted by 1 to 3 halogen atoms        (e.g., a fluorine atom)),    -   p is an integer of 1 or 2];

-   Z¹ is CH;

-   Z² is a group represented by CR^(Z2) wherein R^(Z2) is

-   (1) a C₁₋₆ alkoxy group (e.g., methoxy),

-   (2) a C₃₋₈ cycloalkyl group (e.g., cyclopropyl), or

-   (3) a C₁₋₆ alkyl group (e.g., methyl);

-   Z³ is CH; and

-   B is a pyridine ring.

Specific examples of compound (1) include compounds of Examples 1-280.

Examples of the salt of the compound represented by the formula (1)include metal salts, ammonium salts, salts with an organic base, saltwith an inorganic acid, salts with an organic acid, salts with a basicor acidic amino acid, and the like.

Preferable examples of the metal salt include alkaline metal salts suchas sodium salt, potassium salt and the like; alkaline earth metal saltssuch as calcium salt, magnesium salt, barium salt and the like; aluminumsalt, and the like.

Preferable examples of the salt with an organic base include salts withtrimethylamine, triethylamine, pyridine, picoline, 2,6-lutidine,ethanolamine, diethanolamine, triethanolamine, cyclohexylamine,dicyclohexylamine, N,N′-dibenzylethylenediamine and the like.

Preferable examples of the salt with an inorganic acid include saltswith hydrochloric acid, hydrobromic acid, nitric acid, sulfuric acid,phosphoric acid and the like.

Preferable examples of the salt with an organic acid include salts withformic acid, acetic acid, trifluoroacetic acid, phthalic acid, fumaricacid, oxalic acid, tartaric acid, maleic acid, citric acid, succinicacid, malic acid, methanesulfonic acid, benzenesulfonic acid,p-toluenesulfonic acid and the like.

Preferable examples of the salt with a basic amino acid include saltswith arginine, lysine, ornithine and the like. Preferable examples ofthe salt with an acidic amino acid include salt with aspartic acid,glutamic acid and the like.

Among the above-mentioned salts, pharmaceutically acceptable salts arepreferable.

The prodrug of compound (1) means a compound which is converted tocompound (1) with a reaction due to an enzyme, gastric acid and the likeunder the physiological condition in the living body, that is, acompound which is converted to compound (1) by enzymatic oxidation,reduction, hydrolysis and the like; a compound which is converted tocompound (1) by hydrolysis and the like due to gastric acid, and thelike.

Examples of the prodrug of compound (1) include a compound obtained bysubjecting an amino group in compound (1) to an acylation, alkylation orphosphorylation (e.g., a compound obtained by subjecting an amino groupin compound (1) to an eicosanoylation, alanylation,pentylaminocarbonylation,(5-methyl-2-oxo-1,3-dioxolen-4-yl)methoxycarbonylation,tetrahydrofuranylation, pyrrolidylmethylation, pivaloyloxymethylation ortert-butylation); a compound obtained by subjecting a hydroxy group incompound (1) to an acylation, alkylation, phosphorylation or boration(e.g., a compound obtained by subjecting a hydroxy group in compound (1)to an acetylation, palmitoylation, propanoylation, pivaloylation,succinylation, fumarylation, alanylation ordimethylaminomethylcarbonylation); a compound obtained by subjecting acarboxyl group in compound (1) to an esterification or amidation (e.g.,a compound obtained by subjecting a carboxyl group in compound (1) to aC₁₋₆ alkyl esterification, phenyl esterification, carboxymethylesterification, dimethylaminomethyl esterification, pivaloyloxymethylesterification, ethoxycarbonyloxyethyl esterification, phthalidylesterification, (5-methyl-2-oxo-1,3-dioxolen-4-yl)methyl esterification,cyclohexyloxycarbonylethyl esterification or methylamidation) and thelike. Among them, a compound esterified by C₁₋₆ alkyl (e.g., methyl,ethyl, tert-butyl and the like) are preferably used. These compounds canbe produced from compound (1) according to a method known per se.

The prodrug of compound (1) may also be one which is converted intocompound (1) under a physiological condition, such as those described inIYAKUHIN no KAIHATSU (Development of Pharmaceuticals), Vol. 7, Design ofMolecules, p. 163-198, 1990, Published by HIROKAWA SHOTEN.

Each symbol of the compound in the following Reaction Schemes is asdefined above, unless otherwise specified. Each compound described inthe following Reaction Schemes may be in the form of a salt as long asit does not inhibit the reaction. Examples of the salt include thosesimilar to the salt of compound (1).

The compound obtained in each step can be used directly for the nextreaction as the reaction mixture or as a crude product, or can also beisolated according to a conventional method from the reaction mixture,and can also be easily purified according to a separation means (e.g.,recrystallization, distillation, chromatography etc.).

The production methods of the compound of the present invention aredescribed in the following.

Compound (1) (compound (1a) and compound (1b) in the following ReactionScheme 1) can be produced according to a method known per se, forexample, the production method shown in Reaction Scheme 1 to ReactionScheme 7 or a method analogous thereto.

In each of the following production methods, each starting compound usedfor the production of compound (1) may be in the form of a salt.Examples of the salt include those similar to the salt of compound (1).

Each starting compound to be used for the production of compound (1) canbe used directly for the next reaction as the reaction mixture or as acrude product, or can also be isolated according to a conventionalmethod from the reaction mixture, and can also be purified according toa separation means (e.g., extraction, concentration, neutralization,filtration, distillation, recrystallization, chromatography etc.).Examples of the solvent used for the above-mentioned recrystallizationinclude water, alcohols, ethers, hydrocarbons, amides, halogenatedhydrocarbons, nitriles, ketones, esters, sulfoxides, organic acids andthe like. These solvents may be used alone, or two or more kinds ofsolvents may be mixed at a suitable ratio, for example, 1:1-1:10. Inaddition, the compounds in the Reaction Schemes may be commerciallyavailable, or can be produced according to a method known per se or amethod analogous thereto.

When compound (1) and intermediate for the production of compound (1)have a convertible functional group (e.g., a carboxyl group, an aminogroup, a hydroxy group, a carbonyl group, a mercapto group, a C₁₋₆alkoxy-carbonyl group, a C₆₋₁₄ aryloxy-carbonyl group, a C₇₋₁₆aralkyloxy-carbonyl group, a sulfo group, a halogen atom, an optionallyhalogenated C₁₋₆ alkylsulfonyloxy group, a cyano group, an aminocarbonylgroup, a boryl group etc.), various compounds can be produced byconverting such functional group according to a method known per se or amethod analogous thereto.

Carboxyl group can be converted, for example, by reactions such asesterification, reduction, amidation, conversion reaction to optionallyprotected amino group and the like.

Amino group can be converted, for example, by reactions such asamidation, sulfonylation, nitrosation, alkylation, arylation, imidationand the like.

Hydroxy group can be converted, for example, by reactions such asesterification, carbamoylation, sulfonylation, alkylation, fluorination,arylation, oxidation, halogenation and the like.

Carbonyl group can be converted, for example, by reactions such asreduction, oxidation, fluorination, imination (including oximation,hydrazonation), (thio)ketalization, alkylidenation, thiocarbonylationand the like.

Mercapto group can be converted, for example, by reactions such asalkylation, oxidation and the like.

C₁₋₆ alkoxy-carbonyl group, C₆₋₁₄ aryloxy-carbonyl group and C₇₋₁₆aralkyloxy-carbonyl group can be converted, for example, by reactionssuch as reduction, hydrolysis and the like.

Sulfo group can be converted, for example, by reactions such assulfonamidation, reduction and the like.

Halogen atom can be converted, for example, by various nucleophilicsubstitution reactions, various coupling reactions and the like.

Optionally halogenated C₁₋₆ alkylsulfonyloxy group can be converted, forexample, by various nucleophilic substitution reactions, variouscoupling reactions and the like.

Cyano group can be converted, for example, by reactions such asreduction, hydrolysis and the like.

Aminocarbonyl group can be converted, for example, by reactions such asdehydration, reduction and the like.

Boryl group can be converted, for example, by oxidation, variouscoupling reactions and the like.

In each of the above-mentioned reactions, when the compound is obtainedin a free form, it may be converted to a salt according to aconventional method. When it is obtained as a salt, it may be convertedto a free form or other salt according to a conventional method.

The conversion of these functional group can be carried out according toa method known per se, for example, the method described inComprehensive Organic Transformations, Second Edition, Wiley-VCH,Richard C. Larock, or the like.

In each reaction in the production method of compound (1) and eachreaction of the synthesis of the starting materials, when the startingcompound has an amino group, a carboxyl group, a hydroxy group, acarbonyl group or a mercapto group as a substituent, a protecting groupgenerally used in peptide chemistry and the like may be introduced intothese substituents. By removing the protecting group as necessary afterthe reaction, the object compound can be obtained.

Examples of the amino-protecting group include a formyl group; and aC₁₋₆ alkyl-carbonyl group (e.g., acetyl, ethylcarbonyl etc.), aphenylcarbonyl group, a C₁₋₆ alkyl-oxycarbonyl group (e.g.,methoxycarbonyl, ethoxycarbonyl, tert-butoxycarbonyl (Boc) etc.), anallyloxycarbonyl (Alloc) group, a phenyloxycarbonyl group, afluorenylmethoxycarbonyl (Fmoc) group, a C₇₋₁₀ aralkyl-carbonyl group(e.g., benzylcarbonyl etc.), a C₇₋₁₀ aralkyl-oxycarbonyl group (e.g.,benzyloxycarbonyl (Z) etc.), a C₇₋₁₀ aralkyl group (e.g., benzyl etc.),a 2-(trimethylsilyl)ethoxymethyl (SEM) group, a trityl group, aphthaloyl group, an N,N-dimethylaminomethylene group, an allyl group andthe like, each of which optionally has substituent(s), and the like. Asthese substituents, a phenyl group, a halogen atom (e.g., fluorine,chlorine, bromine, iodine etc.), a C₁₋₆ alkyl-carbonyl group (e.g.,methylcarbonyl, ethylcarbonyl, butylcarbonyl etc.), a nitro group andthe like are used, and the number of the substituents is about 1 to 3.

Examples of the carboxyl-protecting group include a C₁₋₆ alkyl group(e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl etc.), anallyl group, a benzyl group, a phenyl group, a trityl group, atrialkylsilyl group and the like, each of which optionally hassubstituent(s). As these substituents, a halogen atom (e.g., fluorine,chlorine, bromine, iodine etc.), a formyl group, a C₁₋₆ alkyl-carbonylgroup (e.g., acetyl, ethylcarbonyl, butylcarbonyl etc.), a nitro groupand the like are used, and the number of the substituents is about 1 to3.

Examples of the hydroxyl-protecting group include a C₁₋₆ alkyl group(e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl etc.), aC₇₋₁₀ aralkyl group (e.g., benzyl etc.), a formyl group, a C₁₋₆alkyl-carbonyl group (e.g., acetyl, ethylcarbonyl etc.), a benzoylgroup, a C₇₋₁₀ aralkyl-carbonyl group (e.g., benzylcarbonyl etc.), atetrahydropyranyl group, a furanyl group, a silyl group and the like,each of which optionally has substituent(s). As these substituents, ahalogen atom (e.g., fluorine, chlorine, bromine, iodine etc.), a C₁₋₆alkyl group (e.g., methyl, ethyl, n-propyl etc.), a phenyl group, aC₇₋₁₀ aralkyl group (e.g., benzyl etc.), a C₁₋₆ alkoxy group (e.g.,methoxy, ethoxy, n-propoxy etc.), a nitro group and the like are used,and the number of the substituents is about 1 to 4.

Examples of the protected carbonyl group include cyclic acetal (e.g.,1,3-dioxane), noncyclic acetal (e.g., di-C₁₋₆ alkylacetal) and the like.

Examples of the mercapto-protecting group include a C₁₋₆ alkyl group, aphenyl group, a trityl group, a C₇₋₁₀ aralkyl group (e.g., benzyl), aC₁₋₆ alkyl-carbonyl group, a benzoyl group, a C₇₋₁₀ aralkyl-carbonylgroup (e.g., benzylcarbonyl), a C₁₋₆ alkoxy-carbonyl group, a C₆₋₁₄aryloxy-carbonyl group (e.g., phenyloxycarbonyl), a C₇₋₁₄aralkyloxy-carbonyl group (e.g., benzyloxycarbonyl,9-fluorenylmethoxycarbonyl), a 2-tetrahydropyranyl group, a C₁₋₆alkylamino-carbonyl group (e.g., methylaminocarbonyl,ethylaminocarbonyl) and the like. These protecting groups are optionallysubstituted by 1 to 3 substituents selected from a halogen atom, a C₁₋₆alkyl group, a C₁₋₆ alkoxy group and a nitro group.

These protecting groups can be introduced and removed by a method knownper se, for example, the method described in Greene's Protective Groupsin Organic Synthesis, 4^(th) Edition, Wiley-Interscience, Theodora W.Greene, Peter G. M. Wuts or the like. Specifically, a method using acid,base, ultraviolet rays, hydrazine, phenylhydrazine, sodiumN-methyldithiocarbamate, tetrabutylammonium fluoride, palladium acetate,trialkylsilyl halide (e.g., trimethylsilyl iodide, trimethylsilylbromide) and the like, a reduction method, and the like can be employed.

When compound (1) is present as a configurational isomer, adiastereomer, a conformer and the like, each can be isolated by a knownmeans. When compound (1) has an optical isomer, racemates can beresolved by a general optical resolution means, whereby an opticallyactive forms ((+) form, (−) form) can be obtained.

When compound (1) has an optical isomer, a stereoisomer, a positionalisomer, a rotamer or a tautomer, these are also encompassed in compound(1), and can be obtained as a single product according to synthesis andseparation methods known per se.

For example, the method of optical resolution may be a method known perse, such as a fractional recrystallization method, a chiral columnmethod, a diastereomer method etc.

1) Fractional Recrystallization Method

A method wherein a salt of a racemate with an optically active compound(e.g., (+)-mandelic acid, (−)-mandelic acid, (+)-tartaric acid,(−)-tartaric acid, (+)-1-phenethylamine, (−)-1-phenethylamine,cinchonine, (−)-cinchonidine, brucine etc.) is formed, which isseparated by a fractional recrystallization method, and if desired, aneutralization step to give a free optical isomer.

2) Chiral Column Method

A method wherein a racemate or a salt thereof is applied to a column (achiral column) for separation of an optical isomer to allow separation.In the case of a liquid chromatography, for example, a mixture of theoptical isomers is applied to a chiral column such as ENANTIO-OVM(manufactured by Tosoh Corporation), CHIRAL series (manufactured byDaicel Chemical Industries, Ltd.) and the like, and developed withwater, various buffers (e.g., phosphate buffer, etc.) and organicsolvents (e.g., ethanol, methanol, isopropanol, acetonitrile,trifluoroacetic acid, diethylamine, etc.) as an eluent, solely or inadmixture to separate the optical isomer. In the case of a gaschromatography, for example, a chiral column such as CP-Chirasil-DeX CB(manufactured by GL Sciences Inc.) and the like is used to allowseparation.

3) Diastereomer Method

A method wherein a racemic mixture is prepared into a diastereomericmixture by chemical reaction with an optically active reagent, which ismade into a single substance by a typical separation means (e.g., afractional recrystallization method, a chromatography method etc.) andthe like, and is subjected to a chemical treatment such as hydrolysisand the like to separate an optically active reagent moiety, whereby anoptical isomer is obtained. For example, when compound (1) containshydroxy group, or primary or secondary amino group within a molecule,the compound and an optically active organic acid (e.g., MTPA[α-methoxy-α-(trifluoromethyl)phenylacetic acid], (−)-menthoxyaceticacid etc.) and the like are subjected to condensation reaction to givediastereomers of the ester compound or the amide compound, respectively.When compound (1) has a carboxyl group, the compound and an opticallyactive amine or an optically active alcohol reagent are subjected tocondensation reaction to give diastereomers of the amide compound or theester compound, respectively. The separated diastereomer is converted toan optical isomer of the original compound by acid hydrolysis or basehydrolysis.

The solvent, acid and base recited in the production methods of thecompound of the present invention are explained in the following.

Examples of the “solvent” include “alcohols”, “ethers”, “hydrocarbons”,“amides”, “halogenated hydrocarbons”, “nitriles”, “ketones”, “esters”,“sulfoxides”, “water” and the like.

Examples of the “alcohols” include methanol, ethanol, 1-propanol,2-propanol, tert-butyl alcohol and the like.

Examples of the “ethers” include diethyl ether, diisopropyl ether,diphenyl ether, tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane,tert-butyl methyl ether and the like.

Examples of the “hydrocarbons” include benzene, toluene, cyclohexane,hexane, petroleum ether and the like.

Examples of the “amides” include N,N-dimethylformamide,N,N-dimethylacetamide, N-methylpyrrolidone, hexamethylphosphorictriamide and the like.

Examples of the “halogenated hydrocarbons” include dichloromethane,chloroform, carbon tetrachloride, 1,2-dichloroethane, chlorobenzene,benzotrifluoride and the like.

Examples of the “nitriles” include acetonitrile, propionitrile and thelike.

Examples of the “ketones” include acetone, ethyl methyl ketone and thelike.

Examples of the “esters” include ethyl acetate, tert-butyl acetate andthe like.

Examples of the “sulfoxides” include dimethyl sulfoxide and the like.

Examples of the “acid” include “organic acids”, “mineral acids”, “Lewisacids” and the like.

Examples of the “organic acids” include formic acid, acetic acid,propionic acid, trifluoroacetic acid, citric acid, methanesulfonic acid,p-toluenesulfonic acid and the like.

Examples of the “mineral acids” include hydrochloric acid, sulfuric acidand the like.

Examples of the “Lewis acids” include boron trichloride, borontribromide and the like.

Examples of the “base” include “inorganic bases”, “basic salts”,“aromatic amines”, “tertiary amines”, “alkali metal hydrides”, “alkalimetals”, “metal amides”, “alkyl metals”, “aryl metals”, “metalalkoxides” and the like.

Examples of the “inorganic bases” include sodium hydroxide, potassiumhydroxide, lithium hydroxide, barium hydroxide and the like.

Examples of the “basic salts” include sodium carbonate, potassiumcarbonate, cesium carbonate, sodium hydrogen carbonate, sodium acetate,ammonium acetate and the like.

Examples of the “aromatic amines” include pyridine, 2,6-lutidine and thelike.

Examples of the “tertiary amines” include triethylamine, tripropylamine,tributylamine, N,N-diisopropylethylamine, cyclohexyldimethylamine,4-dimethylaminopyridine, N,N-dimethylaniline, N-methylpiperidine,N-methylpyrrolidine, N-methylmorpholine,1,8-diazabicyclo[5,4,0]undec-7-ene and the like.

Examples of the “alkali metal hydrides” include sodium hydride,potassium hydride and the like.

Examples of the “alkali metals” include sodium, lithium, potassium andthe like.

Examples of the “metal amides” include sodium amide, lithiumdiisopropylamide, lithium hexamethyldisilazide and the like.

Examples of the “alkyl metals” include butyllithium, sec-butyllithium,tertbutyllithium and the like.

Examples of the “aryl metals” include phenyllithium and the like.

Examples of the “metal alkoxides” include sodium methoxide, sodiumethoxide, sodium tert-butoxide, potassium tert-butoxide and the like.

Compound (1) can be produced, for example, according to the method shownin the following Reaction Scheme 1 or a method analogous thereto.

wherein R⁴ is an optionally substituted C₁₋₆ alkyl group, R is anoptionally substituted C₁₋₆ alkyl group or an amino-protecting group, L¹and L² are each independently a leaving group, and the other symbols areas defined above.

Examples of the amino-protecting group for R include a formyl group; aC₁₋₆ alkyl-carbonyl group (e.g., acetyl, ethylcarbonyl and the like), aphenylcarbonyl group, a C₁₋₆ alkyl-oxycarbonyl group (e.g.,methoxycarbonyl, ethoxycarbonyl, tert-butoxycarbonyl (Boc) and thelike), an allyloxycarbonyl (Alloc) group, a phenyloxycarbonyl group, afluorenylmethoxycarbonyl (Fmoc) group, a C₇₋₁₀ aralkyl-carbonyl group(e.g., benzyl carbonyl and the like), a C₇₋₁₀ aralkyl-oxycarbonyl group(e.g., benzyloxycarbonyl (Z) and the like), a C₇₋₁₀ aralkyl group (e.g.,benzyl and the like), a 2-(trimethylsilyl)ethoxymethyl (SEM) group, atrityl group, a phthaloyl group, an N,N-dimethylaminomethylene group andan allyl group, each optionally having substituent(s), and the like. Theamino-protecting group is preferably a 2,4-dimethoxybenzyl (DMB) groupor a 2-(trimethylsilyl)ethoxymethyl (SEM) group.

Examples of the leaving group for L¹ include a halogen atom, anoptionally halogenated C₁₋₆ alkylsulfonyloxy group, a C₆₋₁₀arylsulfonyloxy group optionally substituted by C₁₋₆ alkyl group(s), andthe like. The leaving group is preferably a halogen atom or anoptionally halogenated C₁₋₆ alkylsulfonyloxy group.

Examples of the leaving group for L² include a halogen atom, anoptionally halogenated C₁₋₆ alkylsulfonyloxy group, an optionallyhalogenated C₁₋₆ alkoxy group, an optionally substituted aryloxy group,a 1-1H-imidazolyl group and the like. The leaving group is preferably ahalogen atom, a 4-nitrophenoxy group or a trichloromethoxy group.

Compounds (2), (3), (6), (10), (11), (13) and (14) may be commerciallyavailable, or can also be produced according to a method known per se ora method analogous thereto.

<Step 1> Compound (4) can be Produced by Reacting Compound (2) withCompound (3).

The amount of compound (3) to be used is generally about 0.5-20 mol,preferably about 1-10 mol, per 1 mol of compound (2).

This reaction is generally carried out in the presence of a base.Examples of the base include tertiary amines, basic salts, metalhydrogen complex compounds, metal alkoxides, metal amides, alkyl metals,aryl metals and the like. The amount of the base to be used is generallyabout 1-100 mol, preferably about 1-10 mol, per 1 mol of compound (2).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include alcohols, ethers,amides, sulfoxides, tertiary amines, mixed solvents thereof and thelike.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally 0-300° C., preferably 20-150° C.

<Step 2> Compound (5) can be Produced from Compound (4).

The conversion of the nitro group to an amino group can be carried outaccording to a method known per se, for example, the method described inReductions in Organic Chemistry, Second Edition, The American ChemicalSociety, 1996, or a method analogous thereto, for example, ahydrogenation reaction, a reaction using a metal or metal salt, or thelike. The next intramolecular amidation reaction mostly proceeds under acondition of the reduction of the nitro group. Where necessary, thisamidation reaction can be promoted by raising the reaction temperatureor adding a suitable acid or base.

Examples of the acid include organic acids, mineral acids and the like.Examples of the base include tertiary amines, aromatic amines, alkalimetal hydrides, basic salts and the like. The amount of the acid or baseto be used is generally about 0.01-100 mol, preferably about 0.01-10mol, per 1 mol of compound (4).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include alcohols, ethers,esters, organic acids, amides, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally 0-200° C., preferably 20-100° C.

<Step 3> Compound (7) can be Produced by Reacting Compound (5) withCompound (6).

The amount of compound (6) to be used is generally about 0.1-10 mol,preferably about 0.3-5 mol, per 1 mol of compound (5).

This reaction may be carried out in the presence of a base. Examples ofthe base include tertiary amines, aromatic amines, alkali metalhydrides, basic salts and the like. The amount of the base to be used isgenerally about 1-100 mol, preferably about 1-10 mol, per 1 mol ofcompound (5).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include halogenatedhydrocarbons, aromatic amines, amides, tertiary amines, ethers,nitriles, esters, hydrocarbons, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally −50-150° C., preferably −20-100°C.

<Step 4> Compound (1a) can be Produced by Reacting Compound (7) withCompound (8).

The amount of compound (8) to be used is generally about 1-10 mol,preferably about 1-5 mol, per 1 mol of compound (7).

This reaction is generally carried out in the presence of a base.Examples of the base include tertiary amines, aromatic amines, alkalimetal hydrides, basic salts, metal alkoxides, inorganic bases and thelike. The amount of the base to be used is generally about 1-100 mol,preferably about 1-10 mol, per 1 mol of compound (7).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include halogenatedhydrocarbons, aromatic amines, amides, sulfoxides, tertiary amines,ethers, nitriles, esters, hydrocarbons, mixed solvents thereof and thelike.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally −20-150° C., preferably 0-100° C.

<Step 5> Compound (1a) can Also be Produced by Reacting Compound (5)with Compound (9).

The amount of compound (9) to be used is generally about 1-10 mol,preferably about 1-3 mol, per 1 mol of compound (5).

This reaction may be carried out in the presence of a base. Examples ofthe base include tertiary amines, aromatic amines, alkali metalhydrides, basic salts, metal amides, alkyl metals, aryl metals and thelike. The amount of the base to be used is generally about 1-10 mol,preferably about 1-3 mol, per 1 mol of compound (5).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include halogenatedhydrocarbons, ethers, nitriles, amides, sulfoxides, tertiary amines,aromatic amines, esters, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally −20-150° C., preferably 0-100° C.

<Step 6> Compound (12) can be Produced by Reacting Compound (10) withCompound (11).

The amount of compound (11) to be used is generally about 0.5-10 mol,preferably about 1-3 mol, per 1 mol of compound (10).

This reaction is generally carried out in the presence of a base.Examples of the base include tertiary amines, aromatic amines, basicsalts, alkali metal hydrides, metal alkoxides, metal amides, alkylmetals, aryl metals and the like. The amount of the base to be used isgenerally about 1-10 mol, preferably about 1-3 mol, per 1 mol ofcompound (10).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include amides,sulfoxides, ethers, nitriles, hydrocarbons, mixed solvents thereof andthe like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally 0-200° C., preferably 20-150° C.

<Step 7> Compound (15) can be Produced by Reacting Compound (12) withCompound (13)

The amount of compound (13) to be used is generally about 1-10 mol,preferably about 1-3 mol, per 1 mol of compound (12)

This reaction is generally carried out in the presence of a base.Examples of the base include tertiary amines, basic salts, alkali metalhydrides, metal alkoxides, metal amides, alkyl metals, aryl metals andthe like. The amount of the base to be used is generally about 1-10 mol,preferably about 1-3 mol, per 1 mol of compound (13).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include sulfoxides,amides, tertiary amines, aromatic amines, alcohols, ethers, mixedsolvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally 0-300° C., preferably 50-200° C.

<Step 8> Compound (15) can Also be Produced by Reacting Compound (5)with Compound (14).

The amount of compound (14) to be used is generally about 1-10 mol,preferably about 1-3 mol, per 1 mol of compound (5).

This reaction is generally carried out in the presence of a base.Examples of the base include metal amides, alkyl metals, aryl metals,alkali metal hydrides, metal alkoxides, inorganic bases, basic salts,tertiary amines, aromatic amines and the like. The amount of the base tobe used is generally 1-10 mol, preferably 1-3 mol, per 1 mol of compound(5).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include amides,sulfoxides, ethers, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally −100-200° C., preferably −80-150°C.

<Step 9> Compound (16) can be Produced by Reacting Compound (15) withCompound (6).

This reaction is carried out in the same manner as in Step 3.

<Step 10> Compound (1b) can be Produced by Reacting Compound (16) withCompound (8)

This reaction is carried out in the same manner as in Step 4.

<Step 11> Compound (1b) can Also be Produced by Reacting Compound (15)with Compound (9).

This reaction is carried out in the same manner as in Step 5.

<Step 12> Compound (1a) can Also be Produced by Subjecting Compound (1b)Wherein R is an Amino-Protecting Group to a Deprotection Reaction.

The removal of the protecting group of compound (1b) can be carried outaccording to a method known per se, for example, the method described inGreene's Protective Groups in Organic Synthesis, 4^(th) Edition,Wiley-Interscience, Theodora W. Greene, Peter G. M. Wuts or the like, ora method analogous thereto. For the removal of the protecting group, forexample, a method using an acid, base or the like, a hydrogenationreaction or the like are employed.

Compound (5) in Reaction Scheme 1 (compound (5a) in the followingReaction Scheme 2 or compound (5) in Reaction Scheme 3) can be produced,for example, according to the method described in Reaction Scheme 2 orReaction Scheme 3 or a method analogous thereto.

wherein R⁵ is an optionally substituted C₁₋₈ alkyl group, R⁶ and R⁷ areeach a hydrogen atom or an optionally substituted C₁₋₆ alkyl group, andthe other symbols are as defined above.

Compounds (17), (18) and (23) may be commercially available, or can alsobe produced according to a method known per se or a method analogousthereto.

<Step 13> Compound (19) can be Produced by Reacting Compound (17) withCompound (18).

The amount of compound (18) to be used is generally about 1-10 mol,preferably about 1-3 mol, per 1 mol of compound (17).

This reaction is generally carried out in the presence of a base.Examples of the base include tertiary amines, aromatic amines, alkalimetal hydrides, basic salts, metal alkoxides, inorganic bases and thelike. The amount of the base to be used is generally about 1-10 mol,preferably about 1-3 mol, per 1 mol of compound (17).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include aromatic amines,halogenated hydrocarbons, amides, sulfoxides, tertiary amines, ethers,nitriles, esters, hydrocarbons, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally −20-150° C., preferably 0-100° C.

<Step 14> Compound (20) can be Produced by Reacting Compound (19) with aNitrating Reagent.

Examples of the nitrating reagent include metal nitrates such as sodiumnitrate, potassium nitrate and the like, acetyl nitrate, dinitrogenpentoxide, nitronium salts, fuming nitric acid, nitric acid, mixed acids(a mixture of sulfuric acid and fuming nitric acid or nitric acid), andmixtures thereof.

The amount of the nitrating reagent to be used is generally about0.8-100 mol, preferably about 1.0-20 mol, per 1 mol of compound (19).When fuming nitric acid, nitric acid, a mixed acid or the like is usedas a nitrating reagent, it may be used in an excess amount as a reactionsolvent.

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include alcohols, ethers,hydrocarbons, amides, halogenated hydrocarbons, nitriles, sulfoxides,organic acids, mineral acids, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 1-120 hr, preferably 1-96 hr.

The reaction temperature is −20-150° C., preferably 0-80° C.

<Step 15> Compound (21) can be Produced by Subjecting Compound (20) to aDeprotection Reaction.

The removal of the protecting group of compound (20) can be carried outaccording to a method known per se, for example, the method described inGreene's Protective Groups in Organic Synthesis, 4^(th) Edition,Wiley-Interscience, Theodora W. Greene, Peter G. M. Wuts or the like, ora method analogous thereto, for example, a method using an acid or base,hydrogenation reaction or the like.

<Step 16> Compound (22) can be Produced from Compound (21).

The conversion of the nitro group to an amino group can be carried outaccording to a method known per se, for example, the method described inReductions in Organic Chemistry, Second Edition, The American ChemicalSociety, 1996 or a method analogous thereto, for example, ahydrogenation reaction, a reaction using a metal or metal salt, or thelike.

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include alcohols, ethers,amides, esters, organic acids, mineral acids, water, mixed solventsthereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally 0-200° C., preferably 20-100° C.

<Step 17> Compound (24) can be Produced by Reacting Compound (22) withCompound (23).

The amount of compound (23) to be used is generally about 1-10 mol,preferably about 1-5 mol, per 1 mol of compound (22)

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include water, alcohols,ethers, esters, amides, nitriles, aromatic amines, organic acids,mineral acids, halogenated hydrocarbons, mixed solvents thereof and thelike.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally −20-150° C., preferably 0-100° C.

<Step 18> Compound (5a) can be Produced by Subjecting Compound (24) to aReduction Reaction.

Examples of the reducing agent include alkali metal hydrides, metalhydrogen complex compounds, borane complexes and the like. The amount ofthe reducing agent to be used is generally about 1-100 mol, preferablyabout 1-10 mol, per 1 mol of compound (24).

Alternatively, this reduction reaction can also be carried out by ahydrogenation reaction. In this case, for example, a catalyst such aspalladium on carbon, palladium hydroxide on carbon, palladium black,platinum on carbon, platinum dioxide, Raney nickel, Raney cobalt and thelike are can be used. The amount of the catalyst to be used is generallyabout 5-1000 wt %, preferably about 10-300 wt %, per 1 mol of compound(24).

The hydrogenation reaction can also be carried out by using varioushydrogen sources instead of gaseous hydrogen. Examples of the hydrogensource include formic acid, ammonium formate, triethylammonium formate,sodium phosphinate, hydrazine and the like. The amount of the hydrogensource to be used is generally about 1-10 mol, preferably about 1-5 mol,per 1 mol of compound (24).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include halogenatedhydrocarbons, alcohols, ethers, esters, aromatic hydrocarbons, saturatedhydrocarbons, amides, organic acids, water, mixed solvents thereof andthe like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-100 hr, preferably 0.5-50 hr.

The reaction temperature is generally −20-100° C., preferably 0-80° C.

wherein R⁸ is an optionally substituted C₁₋₆ alkyl group or anoptionally substituted benzyl group, and the other symbols are asdefined above.

Compounds (25) and (28) may be commercially available, or can also beproduced according to a method known per se or a method analogousthereto.

<Step 19> Compound (26) can be Produced by Reacting Compound (21) withCompound (25).

The amount of compound (25) to be used is generally about 1-10 mol,preferably about 1-5 mol, per 1 mol of compound (21)

This reaction may be carried out in the presence of a base to promotethe reaction. Examples of the base include tertiary amines, aromaticamines, inorganic bases, basic salts and the like. The amount of thebase to be used is generally about 1-10 mol, preferably about 1-5 mol,per 1 mol of compound (25).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include aromatic amines,amides, alcohols, ethers, halogenated hydrocarbons, esters, nitriles,sulfoxide, hydrocarbons, mixed solvents thereof and the like.

The reaction time is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally −30-120° C., preferably −10-100°C.

<Step 20> Compound (27) can be Produced from Compound (26).

This reaction is carried out in the same manner as in Step 16.

<Step 21> Compound (29) can be Produced by Reacting Compound (27) withCompound (28).

This reaction is carried out in the same manner as in Step 13.

<Step 22> Compound (30) can be Produced by Reacting Compound (29) in thePresence of a Base.

Examples of the base include basic salts, alkali metal hydrides, metalalkoxides, metal amides, alkyl metals, aryl metals, aromatic amines,tertiary amines and the like. The amount of the base to be used isgenerally about 1-10 mol, preferably about 1-5 mol, per 1 mol ofcompound (29).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include ethers, aromatichydrocarbons, saturated hydrocarbons, amides, halogenated hydrocarbons,nitriles, ketones, esters, sulfoxides, aromatic amines, tertiary amines,mixed solvents thereof and the like.

The reaction time is generally 0.1-48 hr, preferably 0.3-24 hr.

The reaction temperature is generally −70-250° C., preferably −20-100°C.

<Step 23> Compound (5) can be Produced from Compound (30).

This reaction is carried out in the same manner as in Step 15.

Among compound (8) and compound (9) in Reaction Scheme 1, compounds (8a)and (9a) can be produced, for example, according to the method shown inReaction Scheme 4 or a method analogous thereto.

wherein R⁹ is a hydrogen atom, an optionally substituted C₁₋₆ alkylgroup, an optionally substituted C₂₋₆ alkenyl group or an optionallysubstituted C₂₋₆ alkynyl group, R¹⁰ is an optionally substituted C₁₋₆alkyl group, an optionally substituted C₂₋₆ alkenyl group, an optionallysubstituted C₂₋₆ alkynyl group or an optionally esterified carboxylgroup, R¹¹ is an optionally substituted C₁₋₆ alkyl group, R¹² is ahydroxy group, an optionally substituted C₁₋₃ alkoxy group or anoptionally substituted benzyl group, R′ is a substituent defined by R⁹and R¹⁰, L³ is a hydrogen atom or a leaving group, L⁴ and L⁵ are each aleaving group, R⁹M¹ or ring AM¹ is an organic metal reagent forintroducing a substituent defined by R⁹ or ring A, and the other symbolsare as defined above.

Examples of the leaving group for L³ include anN,O-dimethylhydroxylamino group, an optionally substituted C₁₋₆ alkoxygroup, a halogen atom and the like.

Examples of the leaving group for L⁴ include a halogen atom, anoptionally halogenated C₁₋₆ alkylsulfonyloxy group and the like.

Examples of the leaving group for L⁵ include a halogen atom, anoptionally halogenated C₁₋₆ alkylsulfonyloxy group, a C₆₋₁₀arylsulfonyloxy group optionally substituted by C₁₋₆ alkyl group(s), andthe like.

Compounds (31), (32), (35), (36), (37), (38), (39), (42) and (45) may becommercially available, or can be produced according to a method knownper se or a method analogous thereto.

<Step 24> Compound (33) Wherein R′ is R¹⁰ can be Produced by ReactingCompound (31) Wherein L³ is a Leaving Group with Compound (32).

The amount of compound (32) to be used is generally about 0.5-10 mol,preferably about 1-5 mol, per 1 mol of compound (31).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include ethers,hydrocarbons, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally −78-150° C., preferably −30-80° C.

<Step 25> Compound (34) Wherein R′ is R¹⁰ can be Produced by ReactingCompound (31) Wherein L³ is a Hydrogen Atom with Compound (32).

The amount of compound (32) to be used is generally about 0.5-10 mol,preferably about 1-5 mol, per 1 mol of compound (31).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include ethers,hydrocarbons, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally −78-150° C., preferably −30-80° C.

<Step 26> Compound (34) can be Produced by Subjecting Compound (33) to aReduction Reaction.

Examples of the reducing agent include alkali metal hydrides, metalhydrogen complex compounds, borane complexes and the like. The amount ofthe reducing agent to be used is generally about 0.25-50 mol, preferablyabout 0.5-5 mol, per 1 mol of compound (33).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include alcohols, ethers,aromatic hydrocarbons, saturated hydrocarbons, water, mixed solventsthereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-100 hr, preferably 0.5-50 hr.

The reaction temperature is generally −78-100° C., preferably −30-80° C.

<Step 27> Compound (33) can be Produced by Subjecting Compound (34) toan Oxidation Reaction.

This reaction is carried out using an oxidizing agent according to aconventional method.

Examples of the oxidizing agent include metal salts or metal oxides suchas chromium(VI) oxide, pyridinium chlorochromate, manganese dioxide andthe like, and organic oxidizing agents such as o-iodoxybenzoic acid(IBX), 1,1,1-triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one(Dess-Martin periodinane) and the like. The amount of the oxidizingagent to be used is generally about 1-100 mol, preferably about 1-50mol, per 1 mol of compound (34).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include halogenatedhydrocarbons, aromatic hydrocarbons, saturated hydrocarbons, nitriles,esters, ethers, sulfoxides, water, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.1-24 hr.

The reaction temperature is generally −78-150° C., preferably −78-100°C.

<Step 28> Compound (33) Wherein R′ is R⁹ can be Produced by ReactingCompound (35) Wherein L³ is a Leaving Group with Compound (36).

This reaction is carried out in the same manner as in Step 24.

<Step 29> Compound (34) Wherein R′ is R⁹ can be Produced by ReactingCompound (35) Wherein L³ is a Hydrogen Atom with Compound (36).

This reaction is carried out in the same manner as in Step 24.

<Step 30> Compound (39) can be Produced by Reacting Compound (37) withZinc Cyanide (38) in the Presence of a Palladium Catalyst.

The amount of the zinc cyanide to be used is generally about 0.5-10 mol,preferably about 1-5 mol, per 1 mol of compound (37).

Examples of the palladium catalyst include palladium(II)acetate,tris(dibenzylideneacetone)dipalladium(0),tetrakis(triphenylphosphine)palladium(0), di-tert-butylphosphinepalladium(0), bis(triphenylphosphine)palladium(II) chloride,[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) chloride and thelike. The amount of the palladium catalyst to be used is generally about0.005-1 mol, preferably about 0.01-1 mol, per 1 mol of compound (37).

This reaction is generally under an inert gas (e.g., argon gas ornitrogen gas) atmosphere or stream in the presence of a phosphineligand. Examples of the phosphine ligand include tert-butylphosphine,triphenylphosphine, 1,1′-bis(diphenylphosphino)ferrocene and the like.The amount of the phosphine ligand to be used is generally about 1-10mol, preferably about 1-5 mol, per 1 mol of the palladium catalyst.Where necessary, a zinc metal may be added to the reaction system. Theamount of the zinc metal to be used is generally about 0.005-10 mol,preferably about 0.01-5 mol, per 1 mol of compound (37).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include amides, ethers,hydrocarbons, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.5-100 hr, preferably 1-48 hr.

The reaction temperature is generally 0-200° C., preferably 20-150° C.

<Step 31> Compound (33) wherein R′ is R⁹ can be produced by reactingcompound (39) with compound (36).

This reaction is carried out in the same manner as in Step 24.

<Step 32> Compound (41) can be Produced by Reacting Compound (37) withan Organotin Reagent (40) in the Presence of a Palladium Catalyst.

Examples of the palladium catalyst include palladium(II)acetate,tris(dibenzylideneacetone)dipalladium(0),tetrakis(triphenylphosphine)palladium(0), di-tert-butylphosphinepalladium(0), bis(triphenylphosphine)palladium(II) chloride,[1,1′-bis(diphenylphosphino)ferrocene]palladium(II) chloride and thelike. The amount of the palladium catalyst to be used is generally about0.005-1 mol, preferably about 0.01-1 mol, per 1 mol of compound (37).

The amount of the organotin reagent (40) to be used is generally about1-10 mol, preferably about 1-5 mol, per 1 mol of compound (37).

This reaction is generally under an inert gas (e.g., argon gas ornitrogen gas) atmosphere or stream in the presence of a phosphineligand. Examples of the phosphine ligand include tert-butylphosphine,triphenylphosphine, 1,1′-bis(diphenylphosphino)ferrocene and the like.The amount of the phosphine ligand to be used is generally about 1-10mol, preferably about 1-5 mol, per 1 mol of the palladium catalyst.

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include hydrocarbons,amides, ethers, sulfoxides, nitriles, water, mixed solvents thereof andthe like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.5-100 hr, preferably 1-48 hr.

The reaction temperature is generally 0-200° C., preferably 20-150° C.

<Step 33> Compound (33) Wherein R′ is a Methyl Group can be Produced bySubjecting Compound (41) to an Acid Hydrolysis Reaction.

Examples of the acid include mineral acids, organic acids and the like.The amount of the acid to be used is generally about 1-100 mol,preferably about 1-10 mol, per 1 mol of compound (41).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include hydrocarbons,alcohols, ethers, nitriles, water, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally 0-150° C., preferably 20-100° C.

<Step 34> Compound (43a) or Compound (43b) can be Produced by ReactingCompound (33) with Compound (42).

(i) Compound (43a) can be produced by subjecting compound (33) to adehydration and condensation reaction with compound (42).

The amount of compound (42) to be used is generally about 1-10 mol,preferably about 1-5 mol, per 1 mol of compound (33).

When compound (42) is in the form of a salt, this reaction is generallycarried out in the presence of a base. Examples of the base includetertiary amines, aromatic amines, basic salts, inorganic bases, alkalimetal hydrides, metal alkoxides and the like. The amount of the base tobe used is generally about 1-10 mol, preferably about 1-5 mol, per 1 molof compound (42).

This reaction can also be promoted by adding a dehydrating agent such asmolecular sieves and the like, p-toluenesulfonic acid, zinc chloride,phosphoryl chloride, boron trifluoride, titanium tetrachloride, aceticacid, trifluoroacetic acid or the like to the reaction system, byremoving water generated in the reaction system using Dean-Stark and thelike, or by a combination thereof.

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include alcohols, ethers,hydrocarbons, esters, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally 0-150° C., preferably 20-100° C.

(ii) Compound (43b) can be produced by subjecting compound (33) to areductive amination reaction with compound (42) (e.g., described in 4thed., Jikken Kagaku Koza, vol. 20, pages 282-284 and 366-368 (JapanChemical Society); J. Am. Chem. Soc., vol. 93, pages 2897-2904, 1971;Synthesis, page 135, 1975, or the like).

In this reaction, compound (43b) is produced by subjecting the iminecompound, which is produced by the dehydration reaction of compound (33)with compound (42), to a reduction reaction.

The amount of compound (42) to be used is generally about 1-10 mol,preferably about 1-3 mol, per 1 mol of compound (33)

The dehydration reaction can also be promoted by adding a dehydratingagent such as molecular sieves and the like, p-toluenesulfonic acid,zinc chloride, phosphoryl chloride, boron trifluoride, titaniumtetrachloride, acetic acid, trifluoroacetic acid or the like to thereaction system, by removing water generated in the reaction systemusing Dean-Stark and the like, or by a combination thereof.

The reduction reaction is generally carried out using a reducing agentaccording to a conventional method. Examples of the reducing agentinclude metal hydrides such as aluminium hydride, diisobutylaluminiumhydride, tributyltin hydride and the like, metal hydrogen complexcompounds such as sodium cyanoborohydride, sodium triacetoxyborohydride,sodium borohydride, lithium aluminium hydride and the like, boranecomplexes such as borane tetrahydrofuran complex, borane dimethylsulfide complex, picoline-borane complex and the like, alkyl boranessuch as thexylborane, disiamyl borane and the like, and the like.

The amount of the reducing agent to be used is generally about 0.25-10mol, preferably about 0.5-5 mol, per 1 mol of compound (33).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include halogenatedhydrocarbons, alcohols, ethers, nitriles, esters, hydrocarbons, amides,organic acids, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-100 hr, preferably 0.5-24 hr.

The reaction temperature is generally −20-200° C., preferably 0-100° C.

<Step 35> Compound (8a) can be Produced from Compound (43a) or Compound(43b).

(i) This reaction is carried out, for example, using a catalyst such aspalladium-carbon, palladium hydroxide, palladium black, platinumdioxide, Raney nickel, Raney cobalt and the like. The amount of thecatalyst to be used is generally about 1-1000 wt %, preferably about5-300 wt %, relative to compound (43a) or compound (43b).

This reaction is also carried out using various hydrogen sources insteadof gaseous hydrogen. Examples of the hydrogen source include formicacid, ammonium formate, triethylammonium formate, sodium phosphinate,hydrazine and the like. The amount of the hydrogen source to be used isgenerally about 1-10 mol, preferably about 1-5 mol, per 1 mol ofcompound (43a) or compound (43b).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include halogenatedhydrocarbons, alcohols, ethers, esters, organic acids, amides, mixedsolvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-100 hr, preferably 0.5-50 hr.

The reaction temperature is generally −20-150° C., preferably 0-100° C.

(ii) When R¹³ is a hydroxy group or an optionally substituted C₁₋₃alkoxy group, compound (8a) can be produced, for example, by subjectingcompound (43a) or compound (43b) to a reduction reaction.

Examples of the reducing agent include borane complexes, metal hydrogencomplex compounds and the like.

The amount of the reducing agent to be used is generally about 0.25-100mol, preferably about 0.5-10 mol, per 1 mol of compound (43a) orcompound (43b).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include ethers, alcohols,water, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally −50-150° C., preferably −20-100°C.

<Step 36> Compound (44) can be Produced from Compound (34).

(i) Compound (44) can be produced, for example, by reacting compound(34) with diphenylphosphoryl azide (DPPA) under the Mitsunobu reactionconditions (e.g., described in Synthesis, pages 1-27, 1981, TetrahedronLett., vol. 36, pages 6373-6374, 1995, Tetrahedron Lett., vol. 38, pages5831-5834, 1997, or the like).

The amount of the DPPA to be used is generally about 1-10 mol,preferably about 1-5 mol, per 1 mol of compound (34).

The amount of the azodicarboxylate and phosphine to be used for thisreaction is generally about 1-10 mol, preferably about 1-5 mol, per 1mol of compound (34), respectively.

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include ethers, aromatichydrocarbons, saturated hydrocarbons, amides, halogenated hydrocarbons,nitriles, ketones, esters, sulfoxides, mixed solvent thereof and thelike.

The reaction time is generally 0.1-100 hr, preferably 0.5-48 hr.

The reaction temperature is generally −20-200° C., preferably 0-100° C.

(ii) Compound (44) can also be produced, for example, by reactingcompound (34) with DPPA in the presence of1,8-diazabicyclo[5.4.0]undec-7-ene (DBU).

The amount of the DPPA to be used is generally about 1-10 mol,preferably about 1-5 mol, per 1 mol of compound (34).

The amount of the DBU to be used is generally about 1-10 mol, preferablyabout 1-5 mol, per 1 mol of compound (34).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include aromatichydrocarbons, saturated hydrocarbons and the like, ethers, amides,esters, nitriles, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally 0-150° C., preferably 20-100° C.

<Step 37> Compound (46) can be Produced from Compound (34).

This reaction is generally carried out using methanesulfonyl chloride,p-toluenesulfonyl chloride or the like, in the presence of a base,according to a conventional method.

Examples of the base include tertiary amines, aromatic amines, basicsalts and the like. The amount of the base to be used is generally about1-10 mol, preferably about 1-5 mol, per 1 mol of compound (34).

The amount of the methanesulfonyl chloride, p-toluenesulfonyl chlorideor the like to be used is generally about 1-10 mol, preferably about 1-5mol, per 1 mol of compound (34).

This reaction can also be carried out by employing the conversionreaction known per se of alcohol to halide usingtriphenylphosphine/carbon tetrachloride, thionyl chloride or the like.

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include ethers, aromaticamines, tertiary amines, halogenated hydrocarbons, hydrocarbons, mixedsolvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.1-24 hr.

The reaction temperature is generally −30-100° C., preferably −10- at60° C.

<Step 38> Compound (46) Wherein L⁵ is a Halogen Atom can be Produced byReacting Compound (45) with a Halogenating Agent.

Examples of the halogenating agent include N-bromosuccinimide,N-chlorosuccinimide, bromine, chlorine, thionyl chloride and the like.The amount of the halogenating agent to be used is generally about 1-50mol, preferably about 1-10 mol, per 1 mol of compound (45).

When N-bromosuccinimide or N-chlorosuccinimide is used as a halogenatingagent, this reaction is generally carried out by heating together with aradical initiator such as azobisisobutyronitrile, benzoyl peroxide orthe like, by light irradiation, or by a combination thereof. The amountof the radical initiator to be used is generally about 0.001-5 mol,preferably about 0.01-1 mol, per 1 mol of compound (45).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include halogenatedhydrocarbons, aromatic hydrocarbons, saturated hydrocarbons, esters,nitriles, ethers, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-100 hr, preferably 0.5-50 hr.

The reaction temperature is generally 0-150° C., preferably 20-100° C.

<Step 39> Compound (44) can be Produced by Reacting Compound (46) withan Azidating Agent.

Examples of the azidating agent include sodium azide, cesium azide,tetrabutylammonium azide and the like. The amount of the azidating agentto be used is generally about 1-50 mol, preferably about 1-10 mol, per 1mol of compound (46).

This reaction can be promoted by adding a crown ether. Examples of thecrown ether include 18-crown-6 and the like. The amount of the crownether to be used is generally about 0.01-20 mol, preferably about 0.1-5mol, per 1 mol of compound (46).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include amides, nitriles,ketones, sulfoxides, esters, ethers, water, mixed solvents thereof andthe like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-100 hr, preferably 0.5-50 hr.

The reaction temperature is generally 0-150° C., preferably 20-100° C.

<Step 40> Compound (8a) can be Produced from Compound (44).

The conversion of the azide group to an amino group can be carried outaccording to a method known per se, for example, the method described inComprehensive Organic Transformations, Second Edition, Wiley-VCH,Richard C. Larock or the like, or a method analogous thereto, forexample, a hydrogenation reaction, Staudinger reaction using atriphenylphosphine, or the like.

<Step 41> Compound (9a) can be Produced by Reacting Compound (8a) withPhosgene or an Equivalent Thereof.

Examples of the equivalent of phosgene includebis(trichloromethyl)carbonate, trichloromethyl chloroformate,1,1′-carbonyldiimidazole and the like. The amount of the phosgene or anequivalent thereof to be used is generally about 0.1-100 mol, preferablyabout 0.3-10 mol, per 1 mol of compound (8a).

This reaction is generally carried out in the presence of a base.Examples of the base include tertiary amines, aromatic amines, basicsalts and the like. The amount of the base to be used is generally 1-100mol, preferably 1-10 mol, per 1 mol of compound (8a).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include halogenatedhydrocarbons, ethers, hydrocarbons, nitriles, water, mixed solventsthereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally −50-200° C., preferably −20-150°C.

Among compound (8) in Reaction Scheme 1, compounds (8b), (8c) and (8d)in Reaction Scheme 5 can be produced, for example, according to themethod shown in Reaction Scheme 5 or a method analogous thereto.

wherein R¹³ is an amino-protecting group, R¹⁴ is an optionallysubstituted C₁₋₆ alkyl group, R¹⁵ is a hydrogen atom or an optionallysubstituted C₁₋₆ alkyl group, and the other symbols are as definedabove.

Compound (33a) may be commercially available, or can be producedaccording to a method known per se or a method analogous thereto.

<Step 42> Compound (8b) can be Produced by Subjecting Compound (33a) toStrecker Reaction.

This reaction is generally carried out by condensing compound (33a) withammonia or an equivalent thereof and hydrogen cyanide or an equivalentthereof to give the corresponding α-aminonitrile (8b).

Examples of the equivalent of ammonia include ammonium chloride,ammonium carbonate, benzyl amine and the like. The amount of the reagentto be used is generally about 1-50 mol, preferably about 1-10 mol, per 1mol of compound (33a).

Examples of the equivalent of hydrogen cyanide include sodium cyanide,potassium cyanide, trimethylsilyl cyanide and the like. The amount ofthe reagent to be used is generally about 1-50 mol, preferably about1-10 mol, per 1 mol of compound (33a).

This reaction may be carried out by adding a Lewis acid such astitanium(IV) tetraisopropoxide and the like. The amount of the Lewisacid to be used is generally about 0.05-50 mol, preferably about 0.1-10mol, per 1 mol of compound (33a).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include alcohols,halogenated hydrocarbons, ethers, hydrocarbons, nitriles, water, mixedsolvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-100 hr, preferably 0.5-48 hr.

The reaction temperature is generally −78-200° C., preferably −78-100°C.

<Step 43> Compound (43) can be Produced by Protecting the Amino Group ofCompound (8b).

The introduction of protecting group in this step can be carried outaccording to a method known per se, for example, the method described inGreene's Protective Groups in Organic Synthesis, 4^(th) Edition,Wiley-Interscience, Theodora W. Greene, Peter G. M. Wuts or the like.

<Step 44> Compound (47) can be Produced from Compound (43).

This reaction can be carried out according to a method known per se, forexample, the method described in Synthesis, vol. 12, pages 949-950,1989, or a method analogous thereto.

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include sulfoxides,water, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-100 hr, preferably 0.5-24 hr.

The reaction temperature is generally −30-100° C., preferably 0-50° C.

<Step 45> Compound (48) can be Produced by Subjecting Compound (47) to aHydrolysis Reaction.

This reaction is carried out using an acid or base according to aconventional method.

Examples of the acid include mineral acids, organic acids and the like.Examples of the base include inorganic bases, basic salts and the like.The amount of the acid or base to be used is generally about 0.5-100mol, preferably about 1-20 mol, per 1 mol of compound (47).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include alcohols, ethers,water, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-100 hr, preferably 0.1-48 hr.

The reaction temperature is generally −10-200° C., preferably 0-150° C.

<Step 46> Compound (49) can be Produced from Compound (33a).

This reaction can be carried out according to a method known per se, forexample, the method described in ORGANIC PREPARATIONS AND PROCEDURESINT., vol. 36, pages 391-443, 2004, or a method analogous thereto.

<Step 47> Compound (8c) can be Produced by Subjecting Compound (49) to aHydrolysis Reaction.

This reaction is carried out in the same manner as in Step 45.

<Step 48> Compound (48) can be Produced by Protecting the Amino Group ofCompound (8c).

This reaction is carried out in the same manner as in Step 43.

Compound (8d) can be produced, for example, from compound (48)successively according to an esterification reaction known per se, areduction reaction known per se, and a deprotection reaction known perse of the protecting group.

Among compound (33) in Reaction Scheme 4, compound (33c) in ReactionScheme 6 can be produced, for example, according to the method shown inReaction Scheme 6 or a method analogous thereto.

wherein R¹⁶ is an optionally substituted C₁₋₆ alkyl group, and the othersymbols are as defined above.

Compound (33a) and compound (33b) may be commercially available, or canbe produced according to a method known per se or a method analogousthereto.

<Step 49> Compound (52) can be Produced by Subjecting Compound (33b) toa Bromination.

Examples of the brominating agent include bromine,phenyltrimethylammonium tribromide, N-bromosuccinimide and the like. Theamount of the brominating agent to be used is generally about 0.5-2 mol,preferably about 0.8-1.5 mol, per 1 mol of compound (33b).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include organic acids,alcohols, ethers, amides, halogenated hydrocarbons, hydrocarbons, water,mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-100 hr, preferably 0.1-48 hr.

The reaction temperature is generally −30-200° C., preferably 0-100° C.

<Step 50> Compound (33c) can be Produced from Compound (52).

(i) This reaction is carried out, for example, by reacting compound (52)with a desirable alcohol (R¹⁶OH) in the presence of silver(I) carbonateor silver(I) oxide and boron trifluoride diethyl ether complex.

The amount of the silver(I) carbonate or silver(I) oxide to be used isgenerally about 1-10 mol, preferably about 1-5 mol, per 1 mol ofcompound (52).

The amount of the boron trifluoride diethyl ether complex to be used isgenerally about 1-10 mol, preferably about 1-5 mol, per 1 mol ofcompound (52).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include alcoholscorresponding to R¹⁶OH, ethers, halogenated hydrocarbons, hydrocarbons,mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-100 hr, preferably 0.1-48 hr.

The reaction temperature is generally −30-150° C., preferably 0-80° C.

(ii) This reaction can also be carried out by reacting compound (52)with the desired alcohol (R¹⁶OH) in the presence of a base.

Examples of the base include tertiary amines, basic salts, metalhydrogen complex compounds, metal alkoxides, metal amides, alkyl metals,aryl metals and the like. The amount of the base to be used is generallyabout 1-10 mol, preferably about 1-5 mol, per 1 mol of compound (52).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include alcoholscorresponding to R¹⁶OH, ethers, amides, sulfoxides, halogenatedhydrocarbons, hydrocarbons, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.5-24 hr.

The reaction temperature is generally 0-150° C., preferably 20-100° C.

<Step 51> Compound (53) can be Produced by Subjecting Compound (33a) toWittig Reaction.

This reaction is carried out, for example, by reacting compound (33a)with phosphorus ylide prepared by methyl(triphenyl)phosphonium salt anda base.

Examples of the base include metal alkoxides, alkyl metals, alkali metalhydrides, metal amides and the like. The amount of the base to be usedis generally about 1-10 mol, preferably about 1-5 mol, per 1 mol ofcompound (33a).

The amount of the methyl(triphenyl)phosphonium salt to be used isgenerally about 1-10 mol, preferably about 1-5 mol, per 1 mol ofcompound (33a).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include ethers,halogenated hydrocarbons, hydrocarbons, sulfoxides, mixed solventsthereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.1-24 hr.

The reaction temperature is generally −78-100° C., preferably 0-100° C.

<Step 52> Compound (54) can be Produced by Reacting Compound (53) withan Oxidizing Agent.

Examples of the oxidizing agent include 3-chloroperbenzoic acid,peracetic acid and the like.

The amount of the oxidizing agent to be used is generally about 1-10mol, preferably about 1-5 mol, per 1 mol of compound (53).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include halogenatedhydrocarbons, organic acids, esters, ethers, hydrocarbons, nitriles,water, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.1-24 hr.

The reaction temperature is generally −78-150° C., preferably −20-80° C.

<Step 53> Compound (55) can be Produced by Reacting Compound (54) withthe Alcohol (R¹⁶OH) in the Presence of a Base.

Examples of the base include metal alkoxides prepared from R¹⁶OH, basicsalts, metal hydrogen complex compounds, tertiary amines and the like.The amount of the base to be used is generally about 1-100 mol,preferably about 1-10 mol, per 1 mol of compound (54).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include alcoholscorresponding to R¹⁶OH, amides, halogenated hydrocarbons, ethers,hydrocarbons, nitriles, water, mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.1-48 hr, preferably 0.1-24 hr.

The reaction temperature is generally −30-150° C., preferably 0-100° C.

<Step 54> Compound (33c) can be Produced by Subjecting Compound (55) toan Oxidation Reaction.

This reaction is carried out in the same manner as in Step 27.

Among compound (33) in Reaction Scheme 4, compound (33e) in ReactionScheme 7 can be produced, for example, according to the method shown inReaction Scheme 7 or a method analogous thereto.

wherein R¹⁷ is an optionally substituted C₁₋₆ alkyl group, and the othersymbols are as defined above.

Compound (33d) may be commercially available, or can be producedaccording to a method known per se or a method analogous thereto.

<Step 55> Compound (33e) can be Produced by Reacting Compound (33d) withthe Alcohol (R¹⁷OH) in the Presence of a Palladium(II) Catalyst.

Examples of the palladium(II) catalyst includebis(acetonitrile)palladium chloride, palladium chloride, palladiumacetate and the like. The amount of the palladium(II) catalyst to beused is generally about 0.005-1 mol, preferably about 0.01-1 mol, per 1mol of compound (33d).

The amount of the alcohol (R¹⁷OH) to be used is generally about 1-10mol, preferably about 1-3 mol, per 1 mol of compound (33d).

This reaction is advantageously carried out in a solvent inert to thereaction. The solvent is not particularly limited as long as thereaction proceeds. Preferable examples thereof include halogenatedhydrocarbons, alcohols corresponding to R¹⁷OH, ethers, hydrocarbons,mixed solvents thereof and the like.

While the reaction time varies depending on the reagent and solvent tobe used, it is generally 0.5-48 hr, preferably 1-24 hr.

The reaction temperature is generally 0-100° C., preferably 20-80° C.

Compound (1) obtained in each reaction scheme can be isolated andpurified by known separation and purification means such asconcentration, concentration under reduced pressure, solvent extraction,crystallization, recrystallization, phase transfer, chromatography andthe like. In addition, each material compound used in each reactionscheme can be isolated and purified by those similar to theabove-mentioned known separation and purification means. The materialcompound may be used directly in the next step as the reaction mixturewithout isolation.

When compound (1) has isomers such as an optical isomer, a stereoisomer,a regioisomer and a rotamer and the like, such isomers and a mixturethereof are also encompassed in compound (1). For example, when compound(1) has an optical isomer, the optical isomer resolved from racemate isalso encompassed in compound (I). These isomers can be obtained assingle products according to synthetic methods known per se, separationmethods known per se (e.g., concentration, solvent extraction, columnchromatography, recrystallization etc.), optical resolutions (e.g.,fractional recrystallization method, chiral column method, diastereomermethod and the like).

Compound (1) may be a crystal, and the crystal form may be single or amixture of crystal forms, both of which are encompassed in compound (1).The crystal can be produced according to a crystallization method knownper se.

The compound (1) may be a solvate (e.g., hydrate) or a non-solvate(e.g., non-hydrate etc.) and both are encompassed in compound (1).

The compounds labeled with isotopes (e.g., ³H, ¹⁴C, ³⁵S, ¹²⁵I etc.) andthe like are also encompassed in compound (1).

A deuterium conversion form wherein ¹H is converted to ²H(D) is alsoencompassed in compound (1).

Compound (1) labeled or substituted with an isotope can be used as, forexample, a tracer (PET tracer) used for Positron Emission Tomography(PET), and therefore, it is useful in the fields of medical diagnosisand the like.

Since the compound of the present invention has a superior PDE2Ainhibitory action, shows low toxicity (e.g., phototoxicity, acutetoxicity, chronic toxicity, genetic toxicity, reproductive toxicity,cardiac toxicity, drug interactions, carcinogenicity and the like,particularly phototoxicity), and is superior in stability (particularlymetabolic stability), pharmacokinetics (absorption, distribution,metabolism, excretion etc.) and high solubility, it is useful as amedicament. The compound of the present invention has a PDE2A inhibitoryaction to mammals (e.g., mouse, rat, hamster, rabbit, cat, dog, bovine,horse, sheep, monkey, human etc.), and can be used for the prophylaxisor treatment of the following diseases and symptoms:

-   (1) psychotic disorder (e.g., brief psychotic disorder, shared    psychotic disorder),-   (2) psychosis induced by alcohol, amphetamine, cannabis, cocaine,    hallucinogens, obesity, inhalants, opioids or phencyclidine,-   (3) delusional disorder,-   (4) anxiety disorder,-   (5) movement disorder,-   (6) mood disorder,-   (7) major depressive disorder,-   (8) a major depressive disorder superimposed on a psychotic disorder    (including delusional disorder and schizophrenia),-   (9) major depressive episode of the mild, moderate or severe type,-   (10) manic or mixed mood episode,-   (11) hypomanic mood episode,-   (12) depressive episode with atypical features,-   (13) depressive episode with melancholic features,-   (14) depressive episode with catatonic features,-   (15) mood episode with postpartum onset;-   (16) post-stroke depression,-   (17) dysthymic disorder,-   (18) minor depressive disorder,-   (19) autism;-   (20) drug addiction,-   (21) neurodegenerative disorder,-   (22) neurodegeneration associated with cerebral trauma,-   (23) neurodegeneration associated with stroke,-   (24) neurodegeneration associated with cerebral infarct,-   (25) neurodegeneration associated with hypoglycemia,-   (26) neurodegeneration associated with epileptic seizure,-   (27) neurodegeneration associated with neurotoxin poisoning,-   (28) multi-system atrophy,-   (29) Alzheimer's disease,-   (30) dementia,-   (31) multi-infarct dementia,-   (32) alcoholic dementia or other drug-related dementia,-   (33) dementia associated with intracranial tumors or cerebral    trauma,-   (34) dementia associated with Huntington's disease or Parkinson's    disease,-   (35) AIDS-related dementia,-   (36) frontotemperal dementia,-   (37) delirium,-   (38) amnestic disorder,-   (39) post-traumatic stress disorder,-   (40) mental retardation,-   (41) learning disorder (e.g., reading disorder, mathematics    disorder, or a disorder of written expression),-   (42) attention-deficit/hyperactivity disorder;-   (43) age-related cognitive decline,-   (44) premenstrual dysphoric disorder,-   (45) post-psychotic depressive disorder of schizophrenia,-   (46) bipolar disorder (including bipolar I disorder and bipolar II    disorder),-   (47) cyclothymic disorder,-   (48) Parkinson's disease,-   (49) Huntington's disease,-   (50) paranoia,-   (51) schizophrenia (e.g., paranoid schizophrenia, disorganized    schizophrenia, catatonic schizophrenia, undifferentiated    schizophrenia, residual schizophrenia),-   (52) schizophreniform disorder,-   (53) schizoaffective disorder of the delusional type or the    depressive type,-   (54) personality disorder of the paranoid type,-   (55) personality disorder of the schizoid type,-   (56) obesity,-   (57) metabolic syndrome,-   (58) non-insulin dependent diabetes (NIDDM),-   (59) glucose intolerance,-   (60) pneumonia, and/or-   (61) osteoarthritis.

In particular, the compound of the present invention is useful for theprophylaxis or treatment of schizophrenia and Alzheimer's disease.

Since the compound of the present invention is superior in metabolicstability, it can be expected to have an excellent therapeutic effect onthe above-mentioned diseases even in a low dose.

Since the compound of the present invention has low toxicity, apharmaceutical composition containing the compound of the presentinvention (hereinafter to be referred to as the “medicament of thepresent invention”) is obtained as, for example, tablet (includingsugar-coated tablet, film-coated tablet, sublingual tablet, orallydisintegrating tablet, buccal tablet and the like), pill, powder,granule, capsule (including soft capsule, microcapsule), troche, syrup,liquid, emulsion, suspension, controlled-release preparation (e.g.,immediate-release preparation, sustained-release preparation,sustained-release microcapsule), aerosol, films (e.g., orallydisintegrable films, oral cavity mucosa patch film), injection (e.g.,subcutaneous injection, intravenous injection, intramuscular injection,intraperitoneal injection), drip infusion, transdermal absorption typepreparation, ointment, lotion, adhesive preparation, suppository (e.g.,rectal suppository, vaginal suppository), pellet, nasal preparations,pulmonary preparation (inhalant), eye drop and the like by using thecompound of the present invention alone or along with apharmacologically acceptable carrier according to a method known per seas a production method of pharmaceutical preparations (e.g., the methoddescribed in the Japanese Pharmacopoeia etc.). It can be safelyadministered orally or parenterally (e.g., intravenous, intramuscular,subcutaneous, intraorgan, intranasal, intradermal, instillation,intracerebral, rectal, vaginal, intraperitoneal, intratumor, tumorproximal administration, administration to a lesion and the like).

Examples of the pharmacologically acceptable carrier include variousorganic or inorganic carrier substances conventionally used aspreparation materials, which are added as excipient, lubricant, binderor disintegrant for solid preparations; as solvent, solubilizing agent,suspending agent, isotonicity agent, buffer or soothing agent for liquidpreparation, and the like. Where necessary, preparation additives suchas preservative, antioxidant, colorant, sweetener, absorbent, humectantand the like can also be appropriately used in suitable amounts.

Examples of the excipient include lactose, sucrose, D-mannitol,D-sorbitol, starch, pregelatinized starch, cornstarch, dextrin,microcrystalline cellulose, low-substituted hydroxypropyl cellulose,sodium carboxymethylcellulose, gum arabic, pullulan, light anhydroussilicic acid, synthetic aluminum silicate, magnesium aluminatemetasilicate and the like.

Examples of the lubricant include magnesium stearate, calcium stearate,talc, colloidal silica and the like.

Examples of the binder include pregelatinized starch, microcrystallinecellulose, sucrose, gum arabic, D-mannitol, trehalose, dextrin,pullulan, hydroxypropyl cellulose, hydroxypropyl methylcellulose,polyvinylpyrrolidone, starch, saccharose, gelatin, methylcellulose,carboxymethylcellulose, sodium carboxymethylcellulose and the like.

Examples of the disintegrant include lactose, sucrose, starch,carboxymethylcellulose, calcium carboxymethylcellulose, croscarmellosesodium, sodium carboxymethyl starch, light anhydrous silicic acid,low-substituted hydroxypropyl cellulose and the like.

Examples of the solvent include water for injection, physiologicalsaline, Ringer's solution, alcohol, propylene glycol, polyethyleneglycol, macrogol, sesame oil, corn oil, olive oil, cottonseed oil andthe like.

Examples of the solubilizing agent include polyethylene glycol,propylene glycol, D-mannitol, trehalose, benzyl benzoate, ethanol,tris(hydroxymethyl)aminomethane, cholesterol, triethanolamine, sodiumcarbonate, sodium citrate, sodium salicylate, sodium acetate and thelike.

Examples of the suspending agent include surfactants such asstearyltriethanolamine, sodium lauryl sulfate, laurylaminopropionicacid, lecithin, benzalkonium chloride, benzethonium chloride, glycerylmonostearate and the like; and hydrophilic polymers such as polyvinylalcohol, polyvinylpyrrolidone, sodium carboxymethylcellulose,methylcellulose, hydroxymethyl cellulose, hydroxyethyl cellulose,hydroxypropyl cellulose, polysorbate, polyoxyethylene hydrogenatedcastor oil and the like.

Examples of the isotonicity agent include glucose, D-sorbitol, sodiumchloride, glycerol, D-mannitol and the like.

Examples of the buffer include buffers such as phosphates, acetates,carbonates, citrates and the like, and the like.

Examples of the soothing agent include benzyl alcohol and the like.

Examples of the preservative include p-hydroxybenzoate, chlorobutanol,benzyl alcohol, phenethyl alcohol, dehydroacetic acid, sorbic acid andthe like.

Preferred examples of the antioxidant include sulfites, ascorbic acid,α-tocopherols and the like.

Examples of the colorant include water-soluble edible tar pigments(e.g., Food Color Red Nos. 2 and 3, Food Color Yellow Nos. 4 and 5, FoodColor Blue Nos. 1 and 2), water insoluble lake pigments (e.g., aluminumsalts of the above-mentioned water-soluble edible tar pigment), naturalpigments (e.g., beta-carotene, chlorophyll, red iron oxide) and thelike.

Examples of the sweetening agent include saccharin sodium, dipotassiumglycyrrhizinate, aspartame, stevia and the like.

While the content of the compound of the present invention in themedicament of the present invention varies depending on the dosage form,dose of the compound of the present invention, and the like, it is, forexample, about 0.1 to 100 wt %, preferably about 0.1-95 wt %.

While the dose of the compound of the present invention varies dependingon the subject of administration, administration route, target disease,symptom and the like, for example, for oral administration to aschizophrenia patient (adult, about 60 kg weight), it is generally about0.1-about 20 mg/kg body weight, preferably about 0.2-about 10 mg/kg bodyweight, more preferably about 0.5-about 10 mg/kg body weight, which isdesirably administered once to several times (e.g., once to 3 times) aday depending on the symptom.

The compound of the present invention can be administered as a singleactive substance, or can be administered in combination with othermedicaments such as other drugs used in the treatment of psychoticdisorder (particularly schizophrenia and bipolar disorder),obsessive-compulsive disorder, major depression, Parkinson's disease,Alzheimer's disease, cognitive disorder, memory loss and the like,(hereinafter to be abbreviated as concomitant drug).

Examples of the concomitant drug include nicotinic α7 agonists,nicotinic α7 partial agonists, nicotinic α7 positive allostericmodulators, PDE2 inhibitors, PDE4 inhibitors, PDE5 inhibitors, PDE10inhibitors, other PDE inhibitors, calcium channel blockers, muscarinicm1 and m2 modulators, adenosine receptor modulators, ampakines, Glycinetransporter 1 inhibitors, NMDA-R modulators, mGluR modulators, dopaminemodulators, serotonin modulators, selective serotonin reuptakeinhibitors, serotonin and norepinephrine reuptake inhibitors,norepinephrine and dopamine reuptake inhibitors, triple reuptakeinhibitors, cannabinoid modulators, cholinesterase inhibitors (e.g.,donepezil, rivastigmine, galantamine) and the like.

In addition, examples of the concomitant drug include, but are notlimited to, other suitable schizophrenia drugs (e.g., Haloperidol,Clozapine, Olanzapine, Risperidone, Aripiprazole, Ziprasidone,Paliperidone, Quetiapine fumarate etc.), bipolar disorder drug (e.g.,Lithium, Olanzapine, Aripiprazole, Valproic acid etc.), Parkinson'sdisease drugs (e.g., Levodopa, Bromocriptine, Pergolide, Pramipexole,Tolcapone, Procyclidine, Trihexyphenidyl, Benztropine etc.), agents usedin the treatment of major depression (e.g., Amitriptyline, Imipramine,Desipramine, Nortriptyline, Paroxetine, Fluoxetine, Sertraline,Bupropion, Escitalopram, Mirtazapine, Venlafaxine, Duloxetine etc.),agents used in the treatment of Alzheimer's disease (e.g., Galantamine,Tacrine, Donepezil, Rivastigmine, Memantine, Neotropin, Selegiline,Estrogen, Clioquinol etc.), agents used in the treatment of dementia(e.g., Thioridazine, Haloperidol, Risperidone, Tacrine, Donepezil,Rivastigmine etc.), agents used in the treatment of epilepsy (e.g.,Phenytoin, Phenobarbital, Carbamazepine, Valproic acid, Ethosuximide,Gabapentin, Solfeton, Felbatol etc.), agents used in the treatment ofmultiple sclerosis (e.g., Tolterodine, Oxybutynin, Oxycodone, Interferonbeta-1b, Interferon beta-1a, Azathioprine, Methotrexate, Glatirameretc.), agents used in the treatment of Huntington's disease (e.g.,Amitriptyline, Imipramine, Desipramine, Nortriptyline, Paroxetine,Fluoxetine, Sertraline, Tetrabenazine, Haloperidol, Chlorpromazine,Thioridazine, Sulpiride, Quetiapine, Clozapine, Risperidone etc.),agents useful in the treatment of diabetes [e.g, PPAR ligands (e.g.agonists or antagonists such as Rosiglitazone, Troglitazone,Pioglitazone etc.), insulin secretagogues (e.g., sulfonylurea drugs suchas Glyburide, Glimepiride, Chlopropamide, Tolbutamide, Glipizide etc.,and non-sulfonyl secretagogues), α-glucosidase inhibitors (e.g.,Acarbose, Miglitol, Voglibose etc), insulin sensitizers (e.g., PPAR-γagonists (e.g., the glitazones); biguanides, PTP-1B inhibitors, DPP-IVinhibitors, 11beta-HSD inhibitors etc.), hepatic glucose output loweringcompounds (e.g., glucagon antagonists and metformin (e.g., Glucophage,Glucophage XR etc.)), insulin and insulin derivatives (including bothlong and short acting forms and formulations of insulin)], antiobesitydrugs [e.g., β-3 agonists, CB-1 agonists, neuropeptide Y5 inhibitors,Ciliary Neurotrophic Factor and derivatives (e.g., Axokine), appetitesuppressants (e.g., Sibutramine), lipase inhibitors (e.g., Orlistat)etc.].

The dosage form of concomitant drugs is not particularly limited, and isacceptable as long as the compound of the present invention is combinedwith concomitant drugs at the time of administration. Examples of suchdosage forms are as follows:

-   (1) Administration of a single formula obtained simultaneous    formulation of the compound of the present invention with a    concomitant drug,-   (2) Simultaneous administration via the same administration route    for two kinds of formulas obtained by independent formulations of    the compound of the present invention and a concomitant drug,-   (3) Administrations at different times via the same administration    route for two kinds of formulas obtained by independent formulations    of the compound of the present invention and a concomitant drug,-   (4) Simultaneous administration via different administration routes    for two kinds of formulas obtained by independent formulations of    the compound of the present invention and a concomitant drug,-   (5) Administrations at different times via different administration    routes for two kinds of formulas obtained by independent    formulations of the compound of the present invention and a    concomitant drug (e.g., administration in the order of the compound    of the present invention and then a concomitant drug, or    administration in the reversed order).

These forms of administration are summarized below and abbreviated as acombination drug of the present invention.

When administering the combination drug of the present invention, theconcomitant drug and the compound of the present invention can beadministered simultaneously. Alternatively, the compound of the presentinvention can be administered after a concomitant drug is administered,or a concomitant drug can be administered after the compound of thepresent invention is administered. When administering at differenttimes, the time difference depends upon the active ingredients to beadministered, drug forms and methods of administration.

For example, when the concomitant drug or a pharmaceutical compositionthereof is administered first, the compound of the present invention ora pharmaceutical composition thereof can be administered within 1 min.to 3 days, preferably within 10 min to 1 day and more preferably within15 min to 1 hour after the concomitant drug or a pharmaceuticalcomposition thereof is administered. When the compound of the presentinvention or a pharmaceutical composition thereof is administered first,the concomitant drug or a pharmaceutical composition thereof can beadministered within 1 min to 1 day, preferably within 10 min to 6 hoursand more preferably within 15 min to 1 hour after the compound of thepresent invention or a pharmaceutical composition thereof isadministered.

If there are no problems with side effects of the concomitant drugs, anydosages can be set. A dosage as a concomitant drug varies depending ondosages, administration subjects, administration routes, targetdiseases, symptoms, etc. For example, in the case of oral administrationin patients with schizophrenia (adults, body weight of approximately 60kg), a dosage range is generally about 0.1 to 20 mg/kg body weight,preferably from about 0.2 to 10 mg/kg body weight and more preferablyfrom about 0.5 to 10 mg/kg body weight. It is preferable that thisdosage is administered once daily to several times daily (e.g., once to3 times).

If the compound of the present invention is used in combination with aconcomitant drug, the respective dosages can be reduced within a saferange with consideration of the opposite effects of the respectivedrugs.

The combination drug of the present invention exhibits low toxicity. Forexample, the compound of the present invention or (and) the concomitantdrug can be combined with a pharmaceutically acceptable carrieraccording to the known method to prepare a pharmaceutical compositionsuch as tablets (including sugar-coated tablets and film-coatedtablets), powder agents, granular agents, capsules (including softcapsules), liquids, injection solutions, suppositories,sustained-release agents, etc. These compositions can be administeredsafely orally or non-orally (e.g., including local, rectal, venousroutes etc.).

The pharmaceutically acceptable carriers that can be used formanufacturing the combination drug of the present invention can be thesame as those used in the medicament of the present invention asmentioned above.

A mixing ratio between the compound of the present invention and theconcomitant drug in the combination drug of the present invention can beselected appropriately based on the administration subjects,administration routes, diseases and the like.

The concomitant drug in the combination drug of the present inventioncan be combined at an appropriate proportion if two or more drugs arecombined.

A dosage of the concomitant drug can be selected appropriately based onthe dosages used clinically. In addition, a mixing ratio between thecompound of the present invention and the concomitant drug can beselected appropriately based on the administration subjects,administration routes, target diseases, symptoms, combinations, etc. Forexample, if the administration subject is humans, a concomitant drug maybe used in an amount ranging from about 0.01 to 100 parts by weightrelative to 1 part by weight of the compound of the present invention.

For example, the content of the compound of the present invention in thecombination drug of the present invention varies with the form offormulations. Generally, it is present in a range from about 0.01 to99.9 wt %, preferably from about 0.1 to about 50 wt % and morepreferably from about 0.5 to about 20 wt % relative to the entireformula.

The content of the concomitant drug in the combination drug of thepresent invention varies with the form of formulations. Generally it ispresent in a range from about 0.01 to 99.9 wt %, preferably from about0.1 to about 50 wt % and more preferably from about 0.5 to about 20 wt %relative to the entire formula.

The content of an additive such as carriers in the combination drug ofthe present invention varies with the form of formulations. Generally itis present in a range from about 1 to 99.99 wt % and preferably fromabout 10 to about 90 wt % relative to the entire formula.

When the compound of the present invention and a concomitant drug areformulated independently, the same contents can be applied.

Since the dosages may fluctuate under various conditions as mentionedabove, a dosage less than the dosages may be sufficient or it may benecessary to administer at a dosage exceeding the range.

EXAMPLE

The present invention is explained in detail in the following byreferring to Examples, Formulation Examples and Experimental Examplesand which are merely exemplified and not to be construed as limitative,and the invention may be changed within the scope of the presentinvention. In the following Examples, the “room temperature” generallymeans about 10° C. to about 35° C. The ratios indicated for mixedsolvents are volume mixing ratios, unless otherwise specified. % meanswt %, unless otherwise specified.

In silica gel column chromatography, NH means use ofaminopropylsilane-bonded silica gel. In HPLC (high performance liquidchromatography), C18 means use of octadecyl-bound silica gel. The ratiosof elution solvents are volume mixing ratios, unless otherwisespecified.

¹H NMR (proton nuclear magnetic resonance spectrum) was measured byFourier-transform type NMR. Peaks with very mild protons such as ahydroxyl group, an amino group and the like are not described.

In the following Reference Examples and Examples, mass spectrum (MS),nuclear magnetic resonance spectrum (NMR) and melting point weremeasured by the following apparatus.

MS (mass spectrum) was measured by LC/MS (liquid chromatograph massspectrometer). As the ionization method, API (Atmospheric PressureIonization, atmospheric pressure chemical ionization) method or ESI(Electron Spray Ionization) method was used. The data indicate measuredvalue (found) found. Generally, a molecular ion peak is observed. In thecase of a compound having an amino group (—NH₂), a peak afterelimination of NH₃ may be observed as a fragment ion. In the case of asalt, a molecular ion peak or fragment ion peak of free form isgenerally observed.

Example 1N-(1-(4-methoxyphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(3-nitropyridin-2-yl)glycinate

To a solution of methyl glycinate hydrochloride (1.98 g) and2-chloro-3-nitropyridine (2.50 g) in N,N-dimethylformamide (16.0 mL) wasadded triethylamine (5.50 mL). The reaction mixture was stirredovernight at 80° C., and the solvent was evaporated under reducedpressure. The residue was dissolved in ethyl acetate, the ethyl acetatesolution was washed successively with water and saturated brine, anddried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (ethyl acetate/hexane) to give the title compound (2.25g).

MS (API+): [M+H]⁺ 212.0.

B) 3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl N-(3-nitropyridin-2-yl)glycinate (50.0 mg) inethanol (3.00 mL) was added 10% palladium-carbon (containing 50% water,50.0 mg). The reaction mixture was stirred at room temperature for 2 hrunder hydrogen atmosphere, and the catalyst was filtered off. Thefiltrate was stirred overnight at 70° C., and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (methanol/ethyl acetate) to give the title compound (23.5mg).

MS (API+): [M+H]⁺ 150.2.

C) N-hydroxy-1-(4-methoxyphenyl)propan-1-imine

To a solution of 1-(4-methoxyphenyl)propan-1-one (25.0 g) in ethanol(300 mL) were added hydroxylamine hydrochloride (11.6 g) andtriethylamine (17.0 g). The reaction mixture was heated at reflex for 3hr, and the solvent was evaporated under reduced pressure. To theresidue was added water, and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure to give the title compound (26.7 g).

MS (API+): [M+H]⁺ 180.0.

D) 1-(4-methoxyphenyl)propan-1-amine

To a solution of N-hydroxy-1-(4-methoxyphenyl)propan-1-imine (12.4 g) inethanol (300 mL) was added 10% palladium-carbon (containing 50% water,8.19 g). The reaction mixture was stirred overnight at room temperatureunder hydrogen atmosphere, the insoluble substance was filtered off, andthe filtrate was concentrated under reduced pressure. The residue waspurified by silica gel column chromatography (NH, hexane/ethyl acetate)to give the title compound (7.56 g).

¹H NMR (300 MHz, DMSO-d₆) δ 0.76 (3H, t, J=7.4 Hz), 1.30-1.64 (2H, m),1.87 (2H, brs), 3.63 (1H, t, J=6.7 Hz), 3.72 (3H, s), 6.74-6.91 (2H, m),7.15-7.29 (2H, m).

E) 1-(4-methoxyphenyl)propan-1-amine hydrochloride

To a solution of 1-(4-methoxyphenyl)propan-1-amine (6.74 g) in ethylacetate (20 mL) was added 1 M hydrogen chloride/diethyl ether solution(50 mL). The reaction mixture was diluted with ethyl acetate, and theprecipitated solid was collected by filtration. The obtained solid waswashed with ethyl acetate, and dried under reduced pressure to give thetitle compound (7.46 g).

¹H NMR (300 MHz, DMSO-d₆) δ 0.73 (3H, t, J=7.4 Hz), 1.66-1.87 (1H, m),1.89-2.10 (1H, m), 3.76 (3H, s), 3.96-4.11 (1H, m), 6.91-7.03 (2H, m),7.36-7.50 (2H, m), 8.51 (3H, brs).

F)N-(1-(4-methoxyphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of 3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one (23.5 mg) ina mixed solvent of tetrahydrofuran (5 mL) and N,N-dimethylacetamide (1mL) were added triethylamine (65.9 μL) and bis(trichloromethyl)carbonate(46.8 mg) at 0° C. The reaction mixture was stirred at 0° C. for 2 hr,triethylamine (65.9 μL) and 1-(4-methoxyphenyl)propan-1-aminehydrochloride (159 mg) were added thereto at 0° C. The reaction mixturewas stirred at room temperature for 2 hr, water was added thereto, andthe mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (NH, ethyl acetate/hexane), andcrystallized from hexane/isopropyl ether to give the title compound (6.3mg).

MS (API−): [M−H]⁻ 339.0.

¹H NMR (300 MHz, CDCl₃) δ 0.79-1.00 (3H, m), 1.76-1.97 (2H, m), 3.78(3H, s), 4.68 (2H, s), 4.83 (1H, q, J=7.2 Hz), 6.86 (2H, d, J=8.7 Hz),6.96 (1H, dd, J=7.7, 5.1 Hz), 7.08-7.37 (3H, m), 7.97 (1H, dd, J=5.1,1.3 Hz), 9.69 (1H, brs), 10.35 (1H, d, J=7.6 Hz).

Example 22-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 4-(trifluoromethoxy)benzoyl chloride

To a suspension of 4-(trifluoromethoxy)benzoic acid (25.0 g) in toluene(300 mL) was added thionyl chloride (17.3 g) at room temperature. To thereaction mixture was added N,N-dimethylacetamide (1 mL) solution, themixture was stirred at 60° C. for 2 hr, and the solvent was evaporatedunder reduced pressure to give the title compound (25.1 g).

¹H NMR (300 MHz, DMSO-d₆) δ 7.39-7.52 (2H, m), 8.01-8.11 (2H, m).

B) N-methoxy-N-methyl-4-(trifluoromethoxy)benzamide

To a solution of 4-(trifluoromethoxy)benzoyl chloride (25.0 g) intoluene (240 mL) were added N-methoxymethanamine hydrochloride (13.0 g)and N-ethyl-N-(propan-2-yl)propan-2-amine (36.0 g) at room temperature.The reaction mixture was stirred at 60° C. for 1 hr, water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed with saturated brine, and dried over anhydrous sodiumsulfate. The residue was purified by silica gel column chromatography(NH, ethyl acetate), and the solvent was evaporated under reducedpressure to give the title compound (16.1 g).

¹H NMR (300 MHz, DMSO-d₆) δ 3.27 (3H, s), 3.55 (3H, s), 7.35-7.51 (2H,m), 7.64-7.83 (2H, m).

C) 1-(4-(trifluoromethoxy)phenyl)propan-1-one

To a solution of N-methoxy-N-methyl-4-(trifluoromethoxy)benzamide (16.1g) in tetrahydrofuran (200 mL) was added 1 M ethylmagnesiumbromide/tetrahydrofuran solution (97 mL) under ice-cooling. The reactionmixture was stirred at room temperature for 3 hr, 0.5 M hydrochloricacid was added thereto, and the mixture was extracted with ethylacetate. The extract was washed successively with 0.5 M hydrochloricacid and saturated brine, and dried over anhydrous sodium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (12.7 g).

¹H NMR (300 MHz, DMSO-d₆) δ 1.09 (3H, t, J=7.2 Hz), 3.07 (2H, q, J=7.2Hz), 7.45-7.56 (2H, m), 8.04-8.15 (2H, m).

D) N-hydroxy-1-(4-(trifluoromethoxy)phenyl)propan-1-imine

To a solution of 1-(4-(trifluoromethoxy)phenyl)propan-1-one (12.7 g) inethanol (120 mL) were added hydroxylamine hydrochloride (4.86 g) andtriethylamine (7.08 g). The reaction mixture was heated at reflex for 4hr, and the solvent was evaporated under reduced pressure. To theresidue was added water, and the mixture was extracted with ethylacetate. The extract was dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure to give the title compound(13.8 g).

¹H NMR (300 MHz, DMSO-d₆) δ 1.04 (3H, t, J=7.6 Hz), 2.72 (2H, q, J=7.6Hz), 7.32-7.44 (2H, m), 7.71-7.81 (2H, m), 11.31 (1H, s).

E) 1-[4-(trifluoromethoxy)phenyl]propan-1-amine

To a solution of N-hydroxy-1-(4-(trifluoromethoxy)phenyl)propan-1-imine(13.8 g) in ethanol (130 mL) was added 10% palladium-carbon (containing50% water, 3.0 g). The reaction mixture was stirred overnight at roomtemperature under hydrogen atmosphere, the insoluble substance wasfiltered off, and the filtrate was concentrated under reduced pressureto give the title compound (11.3 g).

¹H NMR (400 MHz, DMSO-d₆) δ 0.77 (3H, t, J=7.2 Hz), 1.48-1.63 (2H, m),3.76 (1H, t, J=6.8 Hz), 7.27 (2H, d, J=8.4 Hz), 7.45 (2H, d, J=8.4 Hz).

F) 1-(4-(trifluoromethoxy)phenyl)propan-1-amine hydrochloride

To a solution of 1-(4-(trifluoromethoxy)phenyl)propan-1-amine (11.3 g)in a mixed solvent of ethyl acetate (70 mL) and methanol (10 mL) wasadded 4 M hydrogen chloride/ethyl acetate solution (40 mL). The reactionmixture was stirred for 20 min, the solvent was evaporated under reducedpressure, and diethyl ether was added thereto. The precipitated solidwas collected by filtration, washed with diethyl ether, and dried underreduced pressure to give the title compound (10.12 g).

¹H NMR (300 MHz, DMSO-d₆) δ 0.76 (3H, t, J=7.4 Hz), 1.70-2.11 (2H, m),4.20 (1H, dd, J=9.1, 5.7 Hz), 7.39-7.53 (2H, m), 7.61-7.71 (2H, m), 8.63(3H, brs).

G)2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step F ofExample 1.

MS (API+): [M+H]⁺ 395.2.

¹H NMR (300 MHz, CDCl₃) δ 0.96 (3H, t, J=7.4 Hz), 1.76-1.96 (2H, m),4.67 (2H, s), 4.90 (1H, q, J=7.2 Hz), 6.99 (1H, dd, J=7.6, 4.9 Hz),7.12-7.25 (3H, m), 7.30-7.42 (2H, m), 7.99 (1H, dd, J=5.1, 1.7 Hz), 9.91(1H, s), 10.46 (1H, d, J=7.2 Hz).

Example 3N-(1-(4-methoxyphenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(5-methyl-3-nitropyridin-2-yl)glycinate

The title compound was obtained in the same manner as in Step A ofExample 1.

MS (API+): [M+H]⁺ 226.1.

B) 7-methyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one hydrochloride

To an ethanol solution (100 mL) of methylN-(5-methyl-3-nitropyridin-2-yl)glycinate (1.16 g) was added 10%palladium-carbon (containing 50% water, 1.00 g). The reaction mixturewas stirred at room temperature for 2 hr under hydrogen atmosphere, andthe catalyst was filtered off. The filtrate was stirred at 70° C. for 4hr, 5-10% hydrochloric acid/methanol (10 mL) solution was added thereto,and the mixture was stirred overnight at 70° C. The solvent wasevaporated under reduced pressure, and the obtained residue wascrystallized from hexane/ethyl acetate to give the title compound (1.02g).

MS (API+): [M+H]⁺ 164.2.

C)N-(1-(4-methoxyphenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step F ofExample 1.

MS (API+): [M+H]⁺ 355.1.

¹H NMR (300 MHz, DMSO-d₆) δ 0.82 (3H, t, J=7.2 Hz), 1.67-1.83 (2H, m),2.24 (3H, s), 3.72 (3H, s), 4.39 (2H, d, J=0.8 Hz), 4.70 (1H, q, J=7.1Hz), 6.83-6.92 (2H, m), 7.12 (1H, d, J=1.5 Hz), 7.17-7.26 (2H, m),7.81-7.88 (1H, m), 10.11 (1H, d, J=7.6 Hz), 10.78 (1H, brs).

Example 47-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of 7-methyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-onehydrochloride (200 mg) in a mixed solvent of tetrahydrofuran (10 mL) andN,N-dimethylacetamide (10 mL) were added triethylamine (838 μL) and asolution of bis(trichloromethyl)carbonate (297 mg) in tetrahydrofuran (3mL) at 00° C. The reaction mixture was stirred at 0° C. for 3 hr,triethylamine (698 μL) and a solution of1-[4-(trifluoromethoxy)phenyl]propan-1-amine hydrochloride (1.28 g) in amixed solvent of tetrahydrofuran (3 mL) and N,N-dimethylacetamide (5 mL)were added thereto at 0° C. The reaction mixture was stirred at roomtemperature for 1 hr, water was added thereto, and the mixture wasextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous sodium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (ethyl acetate) to give acrude product. The crude product was purified by HPLC (C18, mobilephase: water/acetonitrile (containing 10 mM NH₄HCO₃)), the obtainedfraction was concentrated under reduced pressure, and the residue wascrystallized from hexane/ethyl acetate to give the title compound (56.3mg).

MS (API+): [M+H]⁺ 409.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.76-0.95 (3H, m), 1.78 (2H, quin, J=7.2Hz), 2.25 (3H, s), 4.38 (2H, s), 4.80 (1H, q, J=7.2 Hz), 7.13 (1H, d,J=1.9 Hz), 7.28-7.37 (2H, m), 7.38-7.48 (2H, m), 7.86 (1H, d, J=1.5 Hz),10.21 (1H, d, J=7.2 Hz), 10.81 (1H, brs).

Example 5 Optically active7-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(56.3 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/2-propanol=850/150) to give the title compound having a shorterretention time (10.2 mg).

MS (API+): [M+H]⁺ 409.1.

¹H NMR (300 MHz, CDCl₃) δ 0.95 (3H, t, J=7.4 Hz), 1.85 (2H, quin, J=7.3Hz), 2.31 (3H, s), 4.66 (2H, s), 4.89 (1H, q, J=6.9 Hz), 7.03 (1H, d,J=1.5 Hz), 7.16 (2H, d, J=8.0 Hz), 7.30-7.39 (2H, m), 7.83 (1H, d, J=1.1Hz), 9.31 (1H, s), 10.33 (1H, d, J=7.2 Hz).

Example 6 Optically active7-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(56.3 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/2-propanol=850/150) to give the title compound having a longerretention time (9.00 mg).

MS (API+): [M+H]⁺ 409.1.

¹H NMR (300 MHz, CDCl₃) δ 0.95 (3H, t, J=7.4 Hz), 1.85 (2H, quin, J=7.3Hz), 2.31 (3H, s), 4.66 (2H, s), 4.89 (1H, q, J=6.9 Hz), 7.04 (1H, d,J=1.5 Hz), 7.16 (2H, d, J=8.0 Hz), 7.29-7.38 (2H, m), 7.83 (1H, d, J=1.1Hz), 9.49 (1H, s), 10.33 (1H, d, J=7.2 Hz).

Example 7N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 4-ethenylphenyl trifluoromethyl ether

To a suspension of potassium 2-methylpropan-2-olate (6.10 g) intetrahydrofuran (80 mL) was added methyl(triphenyl)phosphonium iodide(22.1 g) over 5 min under ice-cooling. The reaction mixture was stirredfor 30 min, and a solution of 4-(trifluoromethoxy)benzaldehyde (8.00 g)in tetrahydrofuran (20 mL) was added slowly thereto. The reactionmixture was stirred at room temperature for 1.5 hr, water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed successively with water and saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(petroleum ether) to give the title compound (5.30 g).

¹H NMR (300 MHz, CDCl₃) δ 5.30 (1H, d, J=10.8 Hz), 5.75 (1H, d, J=17.7Hz), 6.72 (1H, dd, J=17.7, 10.8 Hz), 7.19 (2H, d, J=7.8 Hz), 7.44 (2H,d, J=6.9 Hz).

B) 2-(4-(trifluoromethoxy)phenyl) oxirane

To a solution of 4-ethenylphenyl trifluoromethyl ether (5.30 g) inchloroform (50 mL) was added 3-chloroperbenzoic acid (11.4 g) at roomtemperature. The reaction mixture was stirred at room temperature for 2hr, and washed successively with aqueous sodium thiosulfate solution andsaturated brine. The organic layer was dried over anhydrous sodiumsulfate, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (petroleumether/dichloromethane) to give the title compound (4.20 g).

¹H NMR (400 MHz, CDCl₃) δ 2.76 (1H, dd, J=5.6, 2.4 Hz), 3.16 (1H, dd,J=5.2, 4.0 Hz), 3.87 (1H, dd, J=4.0, 2.8 Hz), 7.20 (2H, d, J=8.0 Hz),7.31 (2H, d, J=8.0 Hz).

C) 2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethanol

To a solution of 2-(4-(trifluoromethoxy)phenyl)oxirane (4.20 g) inN,N-dimethylacetamide (20 mL) was added sodium methoxide (5.56 g) atroom temperature. The reaction mixture was stirred at 60° C. for 3 hr.The reaction mixture was cooled to room temperature, and ethyl acetatewas added thereto. The mixture was washed successively with water andsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (dichloromethane/ethyl acetate) togive the title compound (2.75 g).

¹H NMR (300 MHz, CDCl₃) δ 2.87 (1H, d, J=2.7 Hz), 3.33-3.45 (4H, m),3.55 (1H, dd, J=9.6, 3.0 Hz), 4.92 (1H, d, J=8.7 Hz), 7.22 (2H, d, J=8.1Hz), 7.43 (2H, d, J=8.7 Hz).

D) 2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethanone

To a solution of 2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethanol (2.70g) in dichloromethane (50 mL) was added1,1,1-triacetoxy-1,1-dihydro-1,2-benziodoxol-3(1H)-one (6.28 g) at roomtemperature. The reaction mixture was stirred at room temperature for 2hr, and the insoluble substance was filtered off. The filtrate waswashed successively with sodium thiosulfate and saturated brine, anddried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (dichloromethane) to give the title compound (2.00 g).

¹H NMR (400 MHz, CDCl₃) δ 3.51 (3H, s), 4.68 (2H, s), 7.30 (2H, d, J=8.0Hz), 8.02 (2H, d, J=9.2 Hz).

E) 2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethanamine

To a solution of 2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethanone (2.00g) in ethanol (80 mL) were added potassium carbonate (4.70 g) andhydroxylamine hydrochloride (1.18 g) at room temperature. The reactionmixture was heated at reflex overnight, and the solvent was evaporatedunder reduced pressure. To the residue was added ethyl acetate, and themixture was washed successively with water and saturated brine, anddried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure to give a crude product (1.50 g) ofN-hydroxy-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethanimine. To asolution of the obtained crude product (1.50 g) ofN-hydroxy-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethanimine in methanol(50 mL) was added 10% palladium-carbon (containing 50% water, 0.20 g) atroom temperature. The reaction mixture was stirred overnight at roomtemperature under hydrogen atmosphere. The insoluble substance wasfiltered off, and the filtrate was concentrated under reduced pressureto give the title compound (1.3 g).

¹H NMR (300 MHz, CDCl₃) δ 3.72-3.40 (4H, m), 3.49 (1H, dd, J=9.0, 3.0Hz), 4.22 (1H, dd, J=8.1, 3.6 Hz), 7.20 (2H, d, J=8.1 Hz), 7.42 (2H, d,J=8.1 Hz).

F) 4-nitrophenyl2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate

To a solution of 3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one (1.00 g) in amixed solvent of N,N-dimethylacetamide (60 mL) and pyridine (10 mL) wasadded slowly 4-nitrophenyl chloroformate (1.62 g) under ice-cooling. Thereaction mixture was stirred at room temperature for 1.5 hr, and waterwas added thereto. The precipitated solid was collected by filtration,and washed with water to give the title compound (2.09 g).

MS (API+): [M+H]⁺ 315.0.

G)N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of 4-nitrophenyl2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (157 mg) inN,N-dimethylacetamide (5 mL) were added2-methoxy-1-[4-(trifluoromethoxy)phenyl]ethanamine (118 mg) andtriethylamine (191 μL) at room temperature. The reaction mixture wasstirred at room temperature for 3 hr, aqueous sodium hydrogen carbonatesolution was added thereto, and the mixture was extracted with ethylacetate. The extract was washed successively with 1 M hydrochloric acidand saturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (102 mg).

MS (API+): [M+H]⁺ 411.1.

¹H NMR (300 MHz, DMSO-d₆) δ 3.28 (3H, s), 3.55-3.71 (2H, m), 4.33-4.50(2H, m), 4.99-5.13 (1H, m), 7.11 (1H, dd, J=7.9, 4.9 Hz), 7.27-7.39 (3H,m), 7.42-7.53 (2H, m), 8.00 (1H, dd, J=4.9, 1.7 Hz), 10.51 (1H, d, J=7.4Hz), 10.83 (1H, brs).

Example 8 Optically active2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(907 mg) was resolved by HPLC (column: CHIRALPAK IC, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=400/600) to give the title compound having a shorterretention time (429 mg).

MS (API+): [M+H]⁺ 395.1.

¹H NMR (300 MHz, DMSO-d₆) δ 0.88 (3H, t, J=7.3 Hz), 1.70-1.90 (2H, m),4.41 (2H, s), 4.81 (1H, q, J=7.0 Hz), 7.11 (1H, dd, J=7.7, 5.1 Hz),7.26-7.38 (3H, m), 7.38-7.51 (2H, m), 8.02 (1H, dd, J=4.9, 1.5 Hz),10.35 (1H, d, J=7.2 Hz), 10.83 (1H, brs).

Example 9 Optically active2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(907 mg) was resolved by HPLC (column: CHIRALPAK IC, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=400/600) to give the title compound having a longerretention time (439 mg).

MS (API+): [M+H]⁺ 395.1.

¹H NMR (300 MHz, DMSO-d₆) δ 0.88 (3H, t, J=7.3 Hz), 1.70-1.89 (2H, m),4.41 (2H, s), 4.81 (1H, q, J=6.9 Hz), 7.10 (1H, dd, J=7.7, 5.1 Hz),7.25-7.37 (3H, m), 7.38-7.51 (2H, m), 8.02 (1H, dd, J=5.1, 1.7 Hz),10.34 (1H, d, J=7.5 Hz), 10.82 (1H, brs).

Example 108-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(4-methyl-3-nitropyridin-2-yl)glycinate

The title compound was obtained in the same manner as in Step A ofExample 1.

MS (API+): [M+H]⁺ 226.1.

B) 8-methyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To an ethanol solution (120 mL) of methylN-(4-methyl-3-nitropyridin-2-yl)glycinate (1.31 g) was added 10%palladium-carbon (containing 50% water, 1.00 g). The reaction mixturewas stirred at room temperature for 2 hr under hydrogen atmosphere, andthe catalyst was filtered off. The filtrate was stirred overnight at 80°C., and the solvent was evaporated under reduced pressure. The obtainedresidue was crystallized from hexane/ethyl acetate to give the titlecompound (870 mg).

MS (API+): [M+H]⁺ 164.2.

C)8-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Steps F-G ofExample 7.

MS (API+): [M+H]⁺ 409.1.

¹H NMR (300 MHz, CDCl₃) δ 0.95 (3H, t, J=7.4 Hz), 1.75-1.95 (2H, m),2.32 (3H, s), 4.54-4.74 (2H, m), 4.89 (1H, q, J=7.2 Hz), 6.82-6.91 (1H,m), 7.16 (2H, d, J=7.7 Hz), 7.29-7.40 (2H, m), 7.90 (1H, d, J=5.1 Hz),8.33 (1H, brs), 10.33 (1H, d, J=7.4 Hz).

Example 116-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 4-nitrophenyl6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate

The title compound was obtained in the same manner as in Step A ofExample 1, Step B of Example 10 and Step F of Example 7.

MS (API+): [M+H]⁺ 164.2.

B)6-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 409.1.

¹H NMR (300 MHz, CDCl₃) δ 0.96 (3H, t, J=7.5 Hz), 1.77-1.97 (2H, m),2.47 (3H, s), 4.65 (2H, s), 4.90 (1H, q, J=7.0 Hz), 6.83 (1H, d, J=7.9Hz), 7.17 (2H, d, J=7.9 Hz), 7.31-7.39 (2H, m), 7.50-7.58 (1H, m), 8.79(1H, brs), 10.65 (1H, d, J=7.2 Hz).

Example 12N-(2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-methyl-1-[4-(trifluoromethoxy)phenyl]propan-1-amine hydrochloride

The title compound was obtained in the same manner as in Steps C-F ofExample 2.

MS (API+), found: 217.1.

B)N-(2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 409.1.

¹H NMR (300 MHz, CDCl₃) δ 0.89-1.02 (6H, m), 1.92-2.18 (1H, m),4.57-4.73 (2H, m), 4.76-4.92 (1H, m), 6.96-7.06 (1H, m), 7.09-7.22 (3H,m), 7.24-7.35 (2H, m), 8.03 (1H, dd, J=5.1, 1.7 Hz), 8.74 (1H, brs),10.60 (1H, d, J=7.9 Hz).

Example 13N-(2-hydroxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) ethyl amino(4-(trifluoromethoxy)phenyl)acetate

To a solution of 1-bromo-4-(trifluoromethoxy)benzene (10 g) intetrahydrofuran (200 mL) was added 1.6 M n-butyllithium/hexane solution(31.1 mL) at −78° C., and the mixture was stirred at the sametemperature for 50 min under nitrogen atmosphere. Ethyl2-chloro-2-oxoacetate (6.23 g) was added thereto at the sametemperature, and the reaction mixture was stirred overnight at roomtemperature. The reaction mixture was added to 1 M hydrochloric acidunder ice-cooling, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (ethyl acetate/hexane) to give a crude product (2.50 g)of ethyl oxo-(4-(trifluoromethoxy)phenyl)acetate. The title compound(590 mg) was obtained in the same manner as in Steps D-E of Example 2from the obtained crude product

MS (API+): [M+H]⁺ 264.1.

B) ethyl((tert-butoxycarbonyl)amino)(4-(trifluoromethoxy)phenyl)acetate

To a solution of ethyl amino(4-(trifluoromethoxy)phenyl)acetate (590 mg)in tetrahydrofuran (20 mL) was added tert-butyl dicarbonate (430 mg).The reaction mixture was stirred at room temperature for 2 days, and thesolvent was evaporated under reduced pressure to give the title compound(952 mg).

¹H NMR (300 MHz, CDCl₃) δ 1.22 (3H, t, J=7.2 Hz), 1.53 (9H, s),3.99-4.33 (2H, m), 5.32 (1H, d, J=6.8 Hz), 5.63 (1H, brs), 7.19 (2H, d,J=7.9 Hz), 7.41 (2H, d, J=8.7 Hz).

C) tert-butyl(2-hydroxy-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate

To a suspension of lithium aluminium hydride (41.8 mg) intetrahydrofuran (5 mL) was added ethyl((tert-butoxycarbonyl)amino)(4-(trifluoromethoxy)phenyl)acetate (100 mg) under ice-cooling, and themixture was stirred at the same temperature for 30 min. Anhydrousmagnesium sulfate was added thereto, and then one drop of water andethyl acetate were successively added thereto, and the insolublesubstance was filtered off using Celite. The filtrate was concentratedunder reduced pressure to give the title compound (54.8 mg).

MS (API−): [M−H]⁻ 320.1.

D)N-(2-hydroxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Tert-butyl(2-hydroxy-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate (52mg) was added 2 M hydrogen chloride/ethanol solution (2 mL). Thereaction mixture was stirred at 60° C. for 2 min, and the solvent wasevaporated under reduced pressure. To the residue were addedN,N-dimethylformamide (2 mL), triethylamine (0.045 mL) and 4-nitrophenyl2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (50.9 mg) atroom temperature. The reaction mixture was stirred overnight at roomtemperature, saturated brine was added thereto, and the mixture wasextracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (ethyl acetate/hexane) to give a crude productcontainingN-(2-hydroxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide.The obtained crude product was purified by HPLC (C18, mobile phase:water/acetonitrile (containing 0.1% TFA)), to the obtained fraction wasadded saturated sodium carbonate aqueous solution, and the mixture wasextracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure to give the title compound (32.2 mg).

MS (API+): [M+H]⁺ 397.1.

¹H NMR (300 MHz, DMSO-ds) δ 3.51-3.80 (2H, m), 4.29-4.53 (2H, m), 5.09(1H, t, J=5.1 Hz), 7.11 (1H, dd, J=7.7, 5.1 Hz), 7.28-7.35 (4H, m),7.40-7.51 (2H, m), 8.01 (1H, dd, J=4.9, 1.5 Hz), 10.39 (1H, d, J=7.2Hz), 10.79 (1H, brs).

Example 14N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)tert-butyl(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate

1 M Methylmagnesium bromide/tetrahydrofuran solution (2.20 mL) wasdiluted with tetrahydrofuran (5 mL),ethyl((tert-butoxycarbonyl)amino)(4-(trifluoromethoxy)phenyl)acetate(200 mg) was added thereto at 0° C. The reaction mixture was stirred atthe same temperature for 2 hr, saturated aqueous ammonium chloridesolution was added thereto, and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (ethyl acetate/hexane) to give the title compound (78mg).

MS (API−): [M−H]⁻ 348.2.

B)N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in. Step D ofExample 13

MS (API+): [M+H]⁺0 425.0.

¹H NMR (300 MHz, CDCl₃) δ 1.16 (3H, s), 1.37 (3H, s), 1.70 (1H, s),4.55-4.76 (2H, m), 4.91 (1H, d, J=8.3 Hz), 7.02 (1H, dd, J=7.9, 4.9 Hz),7.13-7.22 (3H, m), 7.37-7.46 (2H, m), 8.07 (1H, dd, J=4.9, 1.5 Hz), 8.51(1H, s), 10.93 (1H, d, J=8.3 Hz).

Example 15N-(cyclopropyl(4-(trifluoromethoxy)phenyl)methyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-cyclopropyl-N-hydroxy-1-(4-(trifluoromethoxy)phenyl)methanimine

The title compound was obtained in the same manner as in Step D ofExample 2.

MS (API+): [M+H]⁺ 246.1.

B) 1-cyclopropyl-1-(4-(trifluoromethoxy)phenyl)methanamine

To a solution of1-cyclopropyl-N-hydroxy-1-(4-(trifluoromethoxy)phenyl)methanimine (4.2g) in ethanol (100 mL) was added 10% palladium-carbon (containing 50%water, 1.823 g). The reaction mixture was stirred at room temperaturefor 1 hr under hydrogen atmosphere, 2 M hydrogen chloride/ethanolsolution (1 mL) was added thereto, and the mixture was stirred overnightunder hydrogen atmosphere. The insoluble substance was filtered off, andthe filtrate was concentrated under reduced pressure. To the residue wasadded 4 M hydrogen chloride/ethyl acetate solution (45 mL), and thesolvent was evaporated under reduced pressure. To the residue was addeddiisopropyl ether, and the precipitated solid was purified by HPLC (C18,mobile phase: water/acetonitrile (containing 0.1% TFA)). To the obtainedfraction was added saturated aqueous sodium hydrogen carbonate solution,and the mixture was extracted with ethyl acetate. The extract was driedover anhydrous magnesium sulfate, and concentrated under reducedpressure to give 1-cyclopropyl-1-(4-(trifluoromethoxy)phenyl)methanamine(0.924 g).

MS (API+), found: 215.2.

C) 1-cyclopropyl-1-(4-(trifluoromethoxy)phenyl)methanamine hydrochloride

The title compound was obtained in the same manner as in Step F ofExample 2.

MS (API+), found: 215.1.

D)N-(cyclopropyl(4-(trifluoromethoxy)phenyl)methyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 407.0.

¹H NMR (300 MHz, CDCl₃) δ 0.35-0.55 (2H, m), 0.55-0.69 (2H, m),1.14-1.31 (1H, m), 4.43-4.55 (1H, m), 4.59-4.77 (2H, m), 7.00 (1H, dd,J=7.9, 4.9 Hz), 7.11-7.22 (3H, m), 7.38-7.48 (2H, m), 8.01 (1H, dd,J=5.1, 1.7 Hz), 8.38 (1H, brs), 10.44 (1H, d, J=7.5 Hz).

Example 162-oxo-N-(1-(4-(trifluoromethoxy)phenyl)butyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(4-(trifluoromethoxy)phenyl)butan-1-amine

To a solution of1-butyl-N-hydroxy-1-(4-(trifluoromethoxy)phenyl)methanimine (4.2 g) inethanol (100 mL) was added 10% palladium-carbon (containing 50% water,1.823 g). The reaction mixture was stirred at room temperature for 1 hrunder hydrogen atmosphere, 2 M hydrogen chloride/ethanol solution (1 mL)was added thereto, and the mixture was stirred overnight under hydrogenatmosphere. The insoluble substance was filtered off, and the filtratewas concentrated under reduced pressure. To the residue was added 4 Mhydrogen chloride/ethyl acetate solution (45 mL), and the solvent wasevaporated under reduced pressure. To the residue was added diisopropylether, and the precipitated solid was purified by HPLC (C18, mobilephase: water/acetonitrile (containing 0.1% TFA)). To the obtainedfraction was added saturated aqueous sodium hydrogen carbonate solution,and the mixture was extracted with ethyl acetate. The extract was driedover anhydrous magnesium sulfate, and concentrated under reducedpressure to give 1-(4-(trifluoromethoxy)phenyl)butan-1-amine (0.524 g).

MS (API+), found: 217.2.

B) 1-(4-(trifluoromethoxy)phenyl)butan-1-amine hydrochloride

The title compound was obtained in the same manner as in Step F ofExample 2.

MS (API+), found: 233.2.

C)2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)butyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 409.0.

¹H NMR (300 MHz, CDCl₃) δ 0.86-1.01 (3H, m), 1.23-1.51 (2H, m),1.68-1.94 (2H, m), 4.58-4.75 (2H, m), 4.96 (1H, q, J=7.5 Hz), 7.00 (1H,dd, J=7.7, 5.1 Hz), 7.10-7.22 (3H, m), 7.31-7.38 (2H, m), 8.00 (1H, dd,J=4.9, 1.5 Hz), 8.99 (1H, s), 10.40 (1H, d, J=7.5 Hz).

Example 171-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-methyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of 3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one (1.40 g) inN,N-dimethylformamide (15 mL) was slowly added 1 M potassium1,1,1,3,3,3-hexamethyldisilazane/tetrahydrofuran solution (6.6 mL) underice-cooling. The reaction mixture was stirred at 0° C. for 30 min, andmethyl iodide (2.00 g) was slowly added thereto at the same temperature.The reaction mixture was stirred overnight at room temperature, and thesolvent was evaporated under reduced pressure. To the residue was addedwater, and the mixture was extracted with ethyl acetate. The extract waswashed successively with water and saturated brine, and the solvent wasevaporated under reduced pressure to give the title compound (1.10 g).

¹H NMR (400 MHz, CDCl₃) δ 3.33 (3H, s), 4.18 (2H, s), 6.73 (1H, dd,J=8.0, 5.2 Hz), 7.06 (1H, d, J=7.2 Hz), 7.78 (1H, d, J=4.4 Hz).

B) 4-nitrophenyl1-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate

To a solution of 1-methyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(0.40 g) in a mixed solvent of N,N-dimethylacetamide (2 mL) and pyridine(1 mL) was added 4-nitrophenyl chloroformate (0.75 g). The reactionmixture was stirred at 45° C. for 30 min, and the solvent was evaporatedunder reduced pressure. To the residue was added water, and the mixturewas extracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (petroleum ether/ethyl acetate) to give thetitle compound (0.30 g).

¹H NMR (300 MHz, CDCl₃) δ 3.43 (3H, s), 4.67 (2H, s), 7.28 (1H, dd,J=8.1, 4.8 Hz), 7.42-7.47 (3H, m), 8.26-8.33 (3H, m).

C)1-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

¹H NMR (300 MHz, CDCl₃) δ 0.97 (3H, t, J=7.5 Hz) 1.83-1.93 (2H, m), 3.36(3H, s), 4.69 (2H, s), 4.91 (1H, q, J=6.9 Hz), 7.09 (1H, dd, J=7.8, 5.1Hz), 7.18 (2H, d, J=8.4 Hz), 7.27-7.37 (3H, m), 8.02 (1H, d, J=4.8 Hz),10.31 (1H, d, J=7.5 Hz).

Example 18N-(1-(4-(difluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 4-(N-hydroxypropanimidoyl)phenol

The title compound was obtained in the same manner as in Step C ofExample 1.

MS (API+): [M+H]⁺ 166.1.

B) 4-(1-aminopropyl)phenol

The title compound was obtained in the same manner as in Step D ofExample 1.

¹H NMR (300 MHz, DMSO-d₆) δ 0.74 (3H, t, J=7.5 Hz), 1.36-1.62 (2H, m),3.56 (1H, t, J=6.6 Hz), 6.59-6.72 (2H, m), 7.02-7.14 (2H, m).

C) tert-butyl(1-(4-hydroxyphenyl)propyl)carbamate

To a solution of 4-(1-aminopropyl)phenol (10.4 g) in tetrahydrofuran(200 mL) were added triethylamine (11.5 mL) and di-tert-butyldicarbonate (19.1 mL). The reaction mixture was stirred at roomtemperature for 2 hr, water was added thereto, and the mixture wasextracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure. The obtained solid was trituratedwith hexane/ethyl acetate, and washed with hexane/ethyl acetate to givethe title compound (13.8 g).

MS (API−): [M−H]⁻ 250.2.

D) tert-butyl(1-(4-(difluoromethoxy)phenyl)propyl)carbamate

Under chlorodifluoromethane atmosphere, to a solution oftert-butyl(1-(4-hydroxyphenyl)propyl)carbamate (833 mg) andbenzyltriethylammonium chloride (226 mg) in tetrahydrofuran (20 mL) wasslowly added 8 M aqueous sodium hydroxide solution under ice-cooling.The reaction mixture was stirred at room temperature for 2 hr, water wasadded thereto, and the mixture was extracted with ethyl acetate. Theextract was washed with saturated brine, and dried over anhydrous sodiumsulfate, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (hexane/ethylacetate) to give the title compound (832 mg).

¹H NMR (300 MHz, DMSO-d₆) δ 0.81 (3H, t, J=7.3 Hz), 1.35 (9H, s),1.49-1.71 (2H, m), 4.26-4.45 (1H, m), 6.90-7.47 (6H, m).

E) 1-(4-(difluoromethoxy)pheny)propan-1-amine hydrochloride

To a solution of tert-butyl(1-(4-(difluoromethoxy)phenyl)propyl)carbamate (830 mg) in ethyl acetate(5 mL) was added 4 M hydrogen chloride/ethyl acetate (10 mL) solution.The reaction mixture was stirred at room temperature for 3 hr, and thesolvent was evaporated under reduced pressure to give the title compound(643 mg).

¹H NMR (300 MHz, DMSO-d₆) δ 0,75 (3H,t, J =7.3 Hz), 1.67-2.10 (2H,m),4.06-4.24 (1H, m), 6.99-7.62 (5H, m), 8.51 (3H, brs).

F)N-(1-(4-(difluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 377.1.

¹H NMR (300 MHz, DMSO-d₆) δ 0.86 (3H, t, J=7.3 Hz), 1.67-1.91 (2H, m),4.41 (2H, s), 4.77 (1H, q, J=7.0 Hz), 6.91-7.50 (7H, m), 7.94-8.10 (1H,m), 10.30 (1H, d, J=7.5 Hz), 10.82 (1H, brs).

Example 192-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-7-(trifluoromethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(3-nitro-5-(trifluoromethyl)pyridin-2-yl)glycinate

To a solution of methyl glycinate hydrochloride (13.9 g) and2-chloro-3-nitro-5-(trifluoromethyl)pyridine (5.0 g) in ethanol (100 mL)was added triethylamine (15.4 mL). The reaction mixture was heated atreflex for 5 hr, and the solvent was evaporated under reduced pressure.The residue was triturated with water, and the solid was collected byfiltration, and washed with ethanol to give the title compound (5.09 g).

¹H NMR (400 MHz, CDCl₃) δ 3.82 (3H, s), 4.43 (2H, d, J=5.2 Hz), 8.63(1H, d, J=2.0 Hz), 8.68 (1H, d, J=2.4 Hz), 8.74 (1H, s).

B) 7-(trifluoromethyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methylN-(3-nitro-5-(trifluoromethyl)pyridin-2-yl)glycinate (5.09 g) in ethanol(200 mL) was added tin(II) chloride dihydrate (20.6 g). The reactionmixture was stirred at 80° C. for 2 hr, and the solvent was evaporatedunder reduced pressure. The residue was dissolved in ethylacetate/ethanol, the pH of the solution was adjusted to 9 with saturatedaqueous ammonia solution, and the insoluble substance was filtered offusing Celite. The filtrate was concentrated under reduced pressure togive the title compound (1.10 g).

¹H NMR (400 MHz, DMSO-d₆) δ 4.04 (2H, s), 7.05 (1H, d, J=1.6 Hz), 7.61(1H, s), 7.93 (1H, s), 10.61 (1H, brs).

C) 4-nitrophenyl2-oxo-7-(trifluoromethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate

To a solution of7-(trifluoromethyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one (300 mg)in a mixed solvent of N,N-dimethylacetamide (2 mL) and pyridine (0.5 mL)was added 4-nitrophenyl chloroformate (418 mg). The reaction mixture wasstirred overnight at 45° C., and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (petroleum ether/ethyl acetate) to give the titlecompound (220 mg).

¹H NMR (400 MHz, CDCl₃) δ 4.63 (2H, s), 7.45 (2H, d, J=8.8 Hz), 7.57(1H, s), 8.31 (2H, d, J=9.2 Hz), 8.44 (1H, s).

D)2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-7-(trifluoromethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of 4-nitrophenyl2-oxo-7-(trifluoromethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate(220 mg) in N,N-dimethylformamide (3 mL) were added1-(4-(trifluoromethoxy)phenyl)propan-1-amine hydrochloride (191 mg) andtriethylamine (0.3 mL) at room temperature. The reaction mixture wasstirred overnight at room temperature, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (petroleum ether/ethyl acetate) to give a crude product.The crude product was purified by HPLC (C18, mobile phase:water/acetonitrile (containing 0.1% TFA)), to the obtained fraction wasadded saturated aqueous sodium hydrogen carbonate solution, and themixture was extracted with ethyl acetate. The extract was dried overanhydrous sodium sulfate, and concentrated under reduced pressure togive the title compound (72 mg).

MS (API+): [M+H]⁺ 463.2.

¹H NMR (400 MHz, CDCl₃) δ 0.97 (3H, t, J=4.0 Hz) 1.84-1.92 (2H, m), 4.71(2H, s), 4.91 (1H, q, J=6.8 Hz), 7.17 (1H, d, J=8.0 Hz), 7.33-7.36 (3H,m), 8.28 (1H, s), 9.62 (1H, s), 10.33 (1H, d, J=7.2 Hz).

Example 202-oxo-7-phenyl-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-iodo-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(140 mg), phenylboronic acid (49 mg) andtetrakis(triphenylphosphine)palladium(0) (37 mg) in 1,2-dimethoxyethane(4 mL) was added 2 M aqueous sodium carbonate solution (2 mL) at roomtemperature. The reaction mixture was stirred overnight at reflux, andextracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified bypreparative TLC (petroleum ether/ethyl acetate) to give the titlecompound (72 mg).

MS (API+): [M+H]⁺ 471.3.

¹H NMR (400 MHz, CDCl₃) δ 0.98 (3H, t, J=7.2 Hz), 1.87-1.93 (2H, m),4.71 (1H, d, J=1.2 Hz), 4.92 (1H, q, J=6.8 Hz), 7.18 (2H, d, J=7.6 Hz),7.36-7.38 (3H, m), 7.41-7.45 (1H, m), 7.47-7.51 (2H, m), 7.55-7.57 (2H,m), 8.24 (1H, d, J=2.0 Hz), 8.79 (1H, s), 10.41 (1H, d, J=7.2 Hz).

Example 216-bromo-3-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamideA) ethyl N-(3,5-dibromopyrazin-2-yl)glycinate

To a solution of 3,5-dibromopyrazin-2-amine (16.0 g) and cesiumcarbonate (26.7 g) in N,N-dimethylformamide (90 mL) was slowly added2-chloroethyl acetate (8.1 mL) at room temperature. The reaction mixturewas stirred overnight at 65° C. under nitrogen atmosphere, water wasadded thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (petroleum ether/ethyl acetate) to give the titlecompound (8.6 g).

¹H NMR (400 MHz, CDCl₃) δ 1.31 (3H, t, J=7.2 Hz), 4.16 (2H, d, J=5.6Hz), 4.25 (2H, q, J=7.2 Hz), 5.75 (1H, brs), 8.04 (1H, s).

B)7-bromo-1-(2,4-dimethoxybenzyl)-3,4-dihydropyrazino[2,3-b]pyrazin-2(1H)-one

To a solution of ethyl N-(3,5-dibromopyrazin-2-yl)glycinate (4.20 g) and2,4-dimethoxybenzyl amine (2.20 g) in dimethyl sulfoxide (5 mL) wasadded N N-diisopropylethylamine (5 mL) at room temperature. The reactionmixture was stirred at 135° C. for 2.5 hr using microwave, and cooled toroom temperature, water was added thereto, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue wascrystallized from methanol to give the title compound (1.2 g).

¹H NMR (300 MHz, CDCl ₃) δ 3.77 (3H, s), 3.81 (3H, s), 4.29 (2H, s),4.92 (1H, s), 5.22(2H, s), 6.38-6.42 (2H, m), 7.10 (1H, d, J =8.1 Hz),7.67 (1H, s).

C)6-bromo-4-(2,4-dimethoxybenzyl)-3-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamide

Under nitrogen atmosphere, to a solution of7-bromo-1-(2,4-dimethoxybenzyl)-3,4-dihydropyrazino[2,3-b]pyrazin-2(1H)-one(1.7 g) in tetrahydrofuran (45 mL) was slowly added triphosgene (0.81 g)at room temperature. The reaction mixture was stirred at 50° C. for 2.5hr, and the solvent was evaporated under reduced pressure. The residuewas diluted with tetrahydrofuran (30 mL), and the mixture was slowlyadded to a solution of 1-(4-(trifluoromethoxy)phenyl)propan-1-aminehydrochloride (1.26 g) and triethylamine (2.15 mL) in tetrahydrofuran(45 mL) at room temperature. The reaction mixture was stirred at 60° C.for 30 min, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (petroleumether/ethyl acetate) to give the title compound (2.5 g).

¹H NMR (400 MHz, CDCl₃) δ 0.93 (3H, t, J=7.2 Hz), 1.79-1.91 (2H, m),3.77 (3H, s), 3.79 (3H, s), 4.72 (2H, dd, J=18.8, 14.8 Hz), 4.86 (1H, q,J=7.2 Hz), 5.23 (2H, dd, J=16.8, 14.4 Hz), 6.38-6.41 (2H, m), 7.15-7.20(3H, m), 7.27-7.33 (2H, m), 7.88 (1H, s), 9.69 (1H, d, J=7.2 Hz).

D)6-bromo-3-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamide

To6-bromo-4-(2,4-dimethoxybenzyl)-3-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamide(300 mg) was added trifluoroacetic acid (3 mL) at room temperature. Thereaction mixture was stirred at 75° C. for 1 hr under nitrogenatmosphere, water was added thereto. The pH of the mixture was adjustedto 10 with 2 M aqueous sodium hydroxide solution, and the mixture wasextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous sodium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (petroleum ether/ethylacetate) to give the title compound (40 mg).

MS (API−): [M−H]⁻ 471.9.

¹H NMR (400 MHz, CDCl₃) δ 0.94 (3H, t, J=7.2 Hz), 1.83-1.91 (2H, m),4.71 (2H, s), 4.87 (1H, q, J=7.2 Hz), 7.17 (2H, d, J=8.4 Hz), 7.31 (2H,d, J=8.4 Hz), 8.00 (1H, s), 8.42 (1H, s), 9.70 (1H, d, J=6.8 Hz).

Example 223-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamide A)4-(2,4-dimethoxybenzyl)-3-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamide

To a solution of6-bromo-4-(2,4-dimethoxybenzyl)-3-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamide(800 mg) in a mixed solvent of tetrahydrofuran (10 mL) and methanol (10mL) was added 10% palladium-carbon (containing 50% water, 120 mg). Thereaction mixture was stirred overnight at 30° C. under hydrogenatmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure. The residue was purified by silicagel column chromatography (petroleum ether/ethyl acetate) to give thetitle compound (610 mg).

¹H NMR (400 MHz, CDCl₃) δ 0.95 (3H, t, J=6.4 Hz), 1.85-1.91 (2H, m),3.76 (3H, s), 3.79 (3H, s), 4.77 (2H, s), 4.90 (1H, q, J=7.2 Hz), 5.27(2H, s), 6.35 (1H, dd, J=11.2, 3.2 Hz), 6.43 (1H, d, J=3.2 Hz), 6.94(1H, d, J=11.2 Hz), 7.17 (2H, d, J=10.8 Hz), 7.34 (2H, d, J=10.8 Hz),7.81 (1H, d, J=3.6 Hz), 7.93 (1H, d, J=3.6 Hz), 10.12 (1H, d, J=10.0Hz).

B)3-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamide

The title compound was obtained in the same manner as in Step D ofExample 21.

MS (API−): [M−H]⁻ 394.0.

¹H NMR (400 MHz, CDCl₃) δ 0.96 (3H, t, J=7.6 Hz), 1.84-1.93 (2H, m),4.72 (2H, s), 4.89 (1H, q, J=7.6 Hz), 7.17 (2H, d, J=8.8 Hz), 7.33 (2H,d, J=8.8 Hz), 7.91 (1H, d, J=2.8 Hz), 7.94 (1H, d, J=2.8 Hz), 9.01 (1H,s), 10.09 (1H, d, J=7.2 Hz).

Example 236-methyl-3-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamide A)4-(2,4-dimethoxybenzyl)-6-methyl-3-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamide

Under nitrogen atmosphere, to a solution of6-bromo-4-(2,4-dimethoxybenzyl)-3-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamide(1.0 g) and (1,1-bis(diphenylphosphino)ferrocene)dichloropalladium(II)(150 mg) in 1,4-dioxane (15 mL) was added 1 M dimethylzinc(II)/hexanesolution (4 mL) at room temperature. The reaction mixture was stirred at80° C. for 30 min under nitrogen atmosphere, water was added thereto,and the mixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and dried over anhydroussodium sulfate, and the solvent was evaporated under reduced pressure.The residue was purified by preparative TLC (petroleum ether/ethylacetate) to give the title compound (730 mg).

¹H NMR (400 MHz, CDCl₃) δ 0.93 (3H, t, J=7.2 Hz), 1.83-1.88 (2H, m),2.39 (3H, s), 3.76 (3H, s), 3.79 (3H, s), 4.73 (2H, s), 4.89 (1H, q,J=7.2 Hz), 5.27 (2H, s), 6.36 (1H, dd, J=8.0, 2.4 Hz), 6.41 (1H, d,J=2.4 Hz), 7.03 (1H, d, J=8.8 Hz), 7.16 (2H, d, J=8.0 Hz), 7.32 (2H, d,J=8.0 Hz), 7.66 (1H, s), 10.0 (1H, d, J=7.2 Hz).

B)6-methyl-3-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamide

To4-(2,4-dimethoxybenzyl)-6-methyl-3-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)-carboxamide(730 mg) was added trifluoroacetic acid (10 mL) at room temperature. Thereaction mixture was stirred at 70° C. for 15 min, and water was addedthereto. The pH of the mixture was adjusted to 10 or more with 4 Maqueous sodium hydroxide solution, and the mixture was extracted withdichloromethane. The extract was dried over anhydrous sodium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by HPLC (C18, mobile phase: water/acetonitrile (containing 0.1%TFA)), to the obtained fraction was added saturated aqueous sodiumhydrogen carbonate solution, and the mixture was extracted with ethylacetate. The extract was dried over anhydrous sodium sulfate, andconcentrated under reduced pressure to give the title compound (150 mg).

MS (API+): [M+H]⁺ 410.2.

¹H NMR (400 MHz, CDCl₃) δ 0.94 (3H, t, J=7.2 Hz), 1.82-1.90 (2H, m),2.45 (3H, s), 4.70 (2H, s), 4.88 (1H, q, J=7.2 Hz), 7.17 (2H, d, J=8.4Hz), 7.32 (2H, d, J=8.4 Hz), 7.77 (1H, s), 8.56 (1H, s), 9.98 (1H, d,J=6.8 Hz).

Example 24N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(548 mg) was resolved by HPLC (column: CHIRALPAK IC, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=400/600) to give the title compound having a shorterretention time (265 mg).

MS (API+): [M+H]⁺ 411.2.

¹H NMR (300 MHz, DMSO-d₆) δ 3.28 (3H, s), 3.54-3.73 (2H, m), 4.31-4.53(2H, m), 4.97-5.14 (1H, m), 7.11 (1H, dd, J=7.9, 4.9 Hz), 7.25-7.39 (3H,m), 7.40-7.54 (2H, m), 8.00 (1H, dd, J=4.9, 1.5 Hz), 10.51 (1H, d, J=7.5Hz), 10.83 (1H, brs).

Example 25N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(548 mg) was resolved by HPLC (column: CHIRALPAK IC, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=400/600) to give the title compound having a longerretention time (273 mg).

MS (API+): [M+H]⁺ 411.1.

¹H NMR (300 MHz, DMSO-d₆) δ 3.28 (3H, s), 3.55-3.71 (2H, m), 4.33-4.51(2H, m), 4.99-5.14 (1H, m), 7.11 (1H, dd, J=7.7, 5.1 Hz), 7.26-7.37 (3H,m), 7.42-7.53 (2H, m), 8.00 (1H, dd, J=4.9, 1.9 Hz), 10.51 (1H, d, J=7.5Hz), 10.83 (1H, brs).

Example 267-iodo-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate

The title compound was obtained in the same manner as in Step A ofExample 19.

¹H NMR (400 MHz, CDCl₃) δ 3.81 (3H, s), 4.37 (2H, d, J=7.6 Hz), 8.45(1H, s), 8.54 (1H, d, J=2.8 Hz), 8.71 (1H, d, J=2.8 Hz).

B) 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

The title compound was obtained in the same manner as in. Step B ofExample 19

¹H NMR (400 MHz, DMSO-de) δ 4.00 (2H, s), 7.17 (1H, d, J=1.6 Hz), 7.50(1H, brs), 7.77 (1H, d, J=1.6 Hz), 10.66 (1H, s).

C)7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

Under nitrogen atmosphere, to a solution of7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one (12.5 g) in a mixedsolvent of N,N-dimethylformamide (200 mL) and dimethyl sulfoxide (600mL) was slowly added 1 M potassium1,1,1,3,3,3-hexamethyldisilazane/tetrahydrofuran solution (63.6 mL)under ice-cooling. The reaction mixture was stirred at 0° C. for 30 min,and [2-(chloromethoxy)ethyl](trimethyl)silane (11.3 mL) was slowly addedthereto at the same temperature. The reaction mixture was stirred atroom temperature for 2 hr, and the solvent was evaporated under reducedpressure. To the residue was added aqueous sodium carbonate solution,and the mixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (dichloromethane/ethyl acetate) to give thetitle compound (6.86 g).

¹H NMR (400 MHz, DMSO-d₆) δ 0.01 (9H, s), 0.90 (2H, t, J=7.6 Hz), 3.59(2H, t, J=8.0 Hz), 4.07 (2H, d, J=1.6 Hz), 5.31 (2H, s), 7.55 (1H, d,J=1.6 Hz), 7.92 (1H, d, J=2.0 Hz).

D)7-iodo-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Under nitrogen atmosphere, to a solution of7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(4.05 g) in tetrahydrofuran (150 mL) was slowly added a solution oftriphosgene (2.37 g) in tetrahydrofuran (15 mL) at room temperature. Thereaction mixture was stirred at 40° C. for 2 hr, and the solvent wasevaporated under reduced pressure. The residue was diluted withtetrahydrofuran (40 mL), and the mixture was slowly added to a solutionof 1-(4-(trifluoromethoxy)phenyl)propan-1-amine hydrochloride (3.07 g)and triethylamine (3.03 g) in tetrahydrofuran (50 mL) at roomtemperature. The reaction mixture was stirred overnight at 60° C., andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (petroleum ether/ethylacetate) to give the title compound (4.08 g).

¹H NMR (400 MHz, CDCl₃) δ 0.01 (9H, s), 0.93 (3H, t, J=9.2 Hz),1.80-1.86 (2H, m), 3.65 (1H, t, J=8.0 Hz), 4.66 (2H, dd, J=17.6, 7.6Hz), 4.87 (1H, q, J=6.8 Hz), 5.27 (2H, dd, J=16.8, 10.8 Hz), 7.16 (2H,d, J=8.0 Hz), 7.31 (2H, d, J=8.8 Hz), 7.95 (1H, d, J=1.6 Hz), 8.24 (1H,d, J=1.6 Hz), 9.86 (1H, d, J=7.2 Hz).

E)7-iodo-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To7-iodo-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(4.08 g) were added trifluoroacetic acid (18 mL) and water (2 mL) atroom temperature. The reaction mixture was stirred at room temperaturefor 1 hr, and the solvent was evaporated under reduced pressure. To theresidue was added aqueous sodium hydrogen carbonate solution, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (petroleum ether/ethyl acetate) togive the title compound (2.64 g).

MS (API+): [M+H]⁺ 521.1.

¹H NMR (400 MHz, CDCl₃) δ 0.95 (3H, t, J=7.2 Hz), 1.81-1.87 (2H, m),4.67 (1H, d, J=2.0 Hz), 4.87 (1H, q, J=6.8 Hz), 7.17 (2H, d, J=8.0 Hz),7.32 (2H, d, J=8.4 Hz), 7.44 (1H, d, J=2.0 Hz), 8.19 (1H, d, J=2.0 Hz),9.20 (1H, s), 10.07 (1H, d, J=7.2 Hz).

Example 272-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-7-vinyl-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-iodo-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(520 mg), 2-ethenyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (231 mg) andtetrakistriphenylphosphine palladium(0) (116 mg) in 1,2-dimethoxyethane(12 mL) was added 2 M aqueous sodium carbonate solution (4 mL) at roomtemperature. The reaction mixture was stirred overnight at reflux, andextracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (petroleum ether/ethyl acetate) to give thetitle compound (372 mg).

MS (API+): [M+H]⁺ 421.1.

¹H NMR (400 MHz, CDCl₃) δ 0.96 (3H, t, J=7.2 Hz), 1.83-1.90 (2H, m),4.80 (1H, d, J=0.8 Hz), 4.90 (1H, q, J=6.8 Hz), 5.38 (1H, d, J=10.8 Hz),5.76 (1H, d, J=17.6 Hz), 6.65 (1H, dd, J=18.0, 10.8 Hz), 7.17 (2H, d,J=7.6 Hz), 7.24 (1H, d, J=1.6 Hz), 7.34 (2H, d, J=8.8 Hz), 8.00 (1H, d,J=1.6 Hz), 9.12 (1H, s), 10.38 (1H, d, J=7.2 Hz).

Example 28N-(1-(biphenyl-4-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)4-(1-(((2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-yl)carbonyl)amino)propyl)phenyltrifluoromethanesulfonate

To a solution ofN-(1-(4-hydroxyphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(1.00 g) in pyridine (30 mL) was slowly added trifluoromethanesulfonicanhydride (0.621 mL) under ice-cooling. The reaction mixture was stirredat room temperature for 3 hr, and the solvent was evaporated underreduced pressure. To the residue was added water, the mixture was washedwith 0.5 M hydrochloric acid, and dried over anhydrous sodium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (1.34 g).

MS (API+): [M+H]⁺ 459.1.

B)N-(1-(biphenyl-4-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of4-(1-(((2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-yl)carbonyl)amino)propyl)phenyltrifluoromethanesulfonate (125 mg) in a mixed solvent of water (1.5 mL)and 1,2-dimethoxyethane (3 mL) were added phenylboronic acid (36.5 mg),potassium carbonate (150 mg) and tetrakistriphenylphosphine palladium(0)(15.7 mg) at room temperature. The reaction mixture was stirred at 150°C. for 20 min under nitrogen atmosphere using microwave, water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas dried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give a crude product. The crudeproduct was purified by HPLC (C18, mobile phase: water/acetonitrile(containing 0.1% TFA)), to the obtained fraction was added saturatedaqueous sodium hydrogen carbonate solution, and the mixture wasextracted with ethyl acetate. The extract was dried over anhydroussodium sulfate, and concentrated under reduced pressure to give thetitle compound (29.8 mg).

MS (API+): [M+H]⁺ 387.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.90 (3H, t, J=7.3 Hz), 1.73-1.94 (2H, m),4.43 (2H, s), 4.82 (1H, q, J=6.9 Hz), 7.11 (1H, dd, J=7.5, 4.9 Hz),7.26-7.52 (6H, m), 7.56-7.71 (4H, m), 8.03 (1H, dd, J=4.9, 1.5 Hz),10.36 (1H, d, J=7.9 Hz), 10.82 (1H, brs).

Example 297-ethyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-7-vinyl-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(177 mg) in methanol (25 mL) was added 10% palladium-carbon (containing50% water, 18 mg) under nitrogen atmosphere. The reaction mixture wasstirred at room temperature for 2 hr under hydrogen atmosphere, thecatalyst was filtered off, and the filtrate was concentrated underreduced pressure. The residue was purified by HPLC (C18, mobile phase:water/acetonitrile (containing 0.1% TFA)), to the obtained fraction wasadded saturated aqueous sodium hydrogen carbonate solution, and themixture was extracted with ethyl acetate. The extract was dried overanhydrous sodium sulfate, and concentrated under reduced pressure togive the title compound (135 mg).

MS (API+): [M+H]⁺ 423.1.

¹H NMR (400 MHz, CDCl₃) δ 0.95 (3H, t, J=7.2 Hz), 1.26 (3H, t, J=7.6Hz), 1.82-1.89 (2H, m), 2.63 (2H, q, J=7.6 Hz), 4.66 (2H, dd, J=20.0,18.4 Hz), 4.90 (1H, q, J=7.2 Hz), 7.04 (1H, d, J=1.6 Hz), 7.16 (1H, d,J=8.4 Hz), 7.34 (2H, d, J=8.8 Hz), 7.85 (1H, d, J=1.6 Hz), 9.32 (1H,brs), 10.38 (1H, d, J=7.2 Hz).

Example 30N-(1-(6-methoxypyridazin-3-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 6-methoxypyridazine-3-carbonitrile

To a solution of 3-chloro-6-methoxypyridazine (5 g) and zinc cyanide(4.87 g) in N,N-dimethylformamide (100 mL) were added1,1′-bis(diphenylphosphino)ferrocene (1.917 g) andtris(dibenzylideneacetone)dipalladium(0) (1.584 g). The reaction mixturewas stirred at 100° C. for 2 days under nitrogen atmosphere, saturatedbrine was added thereto, and the mixture was extracted with ethylacetate and tetrahydrofuran. The extract was washed with saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (ethyl acetate/hexane) to give the titlecompound (3.20 g).

¹H NMR (300 MHz, CDCl₃) δ 4.19-4.28 (3H, m), 7.03-7.15 (1H, m),7.64-7.73 (1H, m).

B) 1-(6-methoxypyridazin-3-yl)propan-1-one

To a solution of 6-methoxypyridazine-3-carbonitrile (1.9 g) intetrahydrofuran (30 mL) was added 3 M ethylmagnesium bromide/diethylether solution (5.62 mL) under ice-cooling. The reaction mixture wasstirred at 0° C. for 1 hr under nitrogen atmosphere, 1 M hydrochloricacid was added thereto at the same temperature, and the mixture wasstirred at room temperature for further 5 min. The reaction mixture wasneutralized with saturated aqueous sodium hydrogen carbonate solution,and extracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (ethyl acetate/hexane) to give the titlecompound (0.323 g).

¹H NMR (300 MHz, CDCl₃) δ 1.25 (3H, t, J=7.2 Hz), 3.35 (2H, q, J=7.4Hz), 4.23 (3H, s), 7.06 (1H, d, J=9.4 Hz), 8.05 (1H, d, J=9.0 Hz).

C) 1-(6-methoxypyridazin-3-yl)propan-1-amine

The title compound was obtained in the same manner as in Steps D-E ofExample 2.

MS (API+): [M+H]⁺ 168.2.

D)N-(1-(6-methoxypyridazin-3-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 343.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.86 (3H, t, J=7.3 Hz), 1.70-1.99 (2H, m),4.01 (3H, s), 4.43 (2H, s), 5.01 (1H, q, J=7.2 Hz), 7.11 (1H, dd, J=7.9,4.9 Hz), 7.18 (1H, d, J=9.0 Hz), 7.32 (1H, dd, J=7.9, 1.5 Hz), 7.62 (1H,d, J=9.0 Hz), 8.02 (1H, dd, J=4.9, 1.5 Hz), 10.42 (1H, d, J=7.5 Hz),10.81 (1H, s).

Example 31N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 3-fluoro-N-methoxy-N-methyl-4-(trifluoromethoxy)benzamide

To a solution of 3-fluoro-4-(trifluoromethoxy)benzoic acid (20 g),N,O-dimethylhydroxylamine hydrochloride (10.5 g) and triethylamine (24.9mL) in N,N-dimethylformamide (300 mL) were added 1-hydroxybenzotriazolemonohydrate (16.4 g) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimidehydrochloride (20.5 g) at room temperature. The reaction mixture wasstirred overnight at room temperature, saturated aqueous sodium hydrogencarbonate solution was added thereto, and the mixture was extracted withethyl acetate. The extract was washed with saturated brine, and driedover anhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure to give the title compound (22.9 g).

¹H NMR (300 MHz, CDCl₃) δ 3.38 (3H, s), 3.56 (3H, s), 7.30-7.42 (1H, m),7.51-7.65 (2H, m).

B) 1-(3-fluoro-4-(trifluoromethoxy)phenyl)propan-1-amine hydrochloride

The title compound was obtained in the same manner as in Steps C-F ofExample 2.

MS (API+), found: 221.1.

C)N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 413.1.

¹H NMR (300 MHz, DMSO-ds) δ 0.77-0.95 (3H, m), 1.81 (2H, quin, J=7.3Hz), 4.35-4.47 (2H, m), 4.81 (1H, q, J=7.2 Hz), 7.11 (1H, dd, J=7.7, 5.1Hz), 7.27 (1H, d, J=8.3 Hz), 7.32 (1H, dd, J=7.9, 1.5 Hz), 7.44-7.58(2H, m), 8.02 (1H, dd, J=4.9, 1.5 Hz), 10.30 (1H, d, J=7.2 Hz), 10.81(1H, s).

Example 32N-(1-(2-methoxy-4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step A ofExample 31, Steps C-F of Example 2 and Step G of Example 7.

MS (API+): [M+H]⁺ 425.1.

¹H NMR (300 MHz, CDCl₃) δ 0.92 (3H, t, J=7.5 Hz), 1.71-1.95 (2H, m),3.88 (3H, s), 4.68 (2H, s), 5.05-5.26 (1H, m), 6.71 (1H, s), 6.77 (1H,d, J=9.4 Hz), 6.94-7.03 (1H, m), 7.13 (1H, brs), 7.22 (1H, d, J=8.3 Hz),8.02 (1H, d, J=4.9 Hz), 10.43 (1H, brs).

Example 33N-(1-(4-hydroxyphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 327.1.

Example 34N-(1-(2-fluoro-4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Steps A-B ofExample 30, Steps D-E of Example 2 and Step G of Example 7.

MS (API+): [M+H]⁺ 413.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.89 (3H, t, J=7.2 Hz), 1.70-1.88 (2H, m),4.40 (2H, s), 5.00 (1H, q, J=7.4 Hz), 7.11 (1H, dd, J=7.9, 4.9 Hz), 7.22(1H, d, J=8.7 Hz), 7.27-7.42 (2H, m), 7.49 (1H, t, J=8.5 Hz), 8.02 (1H,dd, J=4.9, 1.9 Hz), 10.43 (1H, d, J=7.5 Hz), 10.81 (1H, s).

Example 357-cyclopropyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of N-methyl-N-nitrosourea (577 mg) in diethyl ether (10mL) was slowly added 3 M potassium hydroxide solution (6 mL) underice-cooling. The reaction mixture was stirred at the same temperaturefor 30 min, and the organic layer was dried over anhydrous sodiumsulfate, and slowly added to a solution of2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-7-vinyl-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(118 mg) in dichloromethane (10 mL) under ice-cooling. Then,palladium(II) acetate (25 mg) was added thereto, the reaction mixturewas stirred at room temperature for 1 hr, and some drops of acetic acidwas added thereto. The insoluble substance was filtered off, and thefiltrate was concentrated under reduced pressure. The residue waspurified by HPLC (C18, mobile phase: water/acetonitrile (containing 0.1%TFA)), to the obtained fraction was added saturated aqueous sodiumhydrogen carbonate solution, and the mixture was extracted with ethylacetate. The extract was dried over anhydrous sodium sulfate, andconcentrated under reduced pressure to give the title compound (43 mg).

MS (API+): [M+H]⁺ 435.1.

¹H NMR (400 MHz, CDCl₃) δ 0.69-0.73 (2H, m), 0.95 (3H, t, J=7.2 Hz),1.00-1.05 (2H, m), 1.82-1.90 (3H, m), 4.60-4.71 (2H, m), 4.89 (1H, q,J=6.8 Hz), 6.85 (1H, d, J=2.0 Hz), 7.16 (1H, d, J=7.6 Hz), 7.34 (2H, d,J=8.4 Hz), 7.81 (1H, d, J=2.0 Hz), 9.31 (1H, s), 10.30 (1H, d, J=7.2Hz).

Example 367-isopropyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)2-oxo-7-(prop-1-en-2-yl)-N-(1-[4-(trifluoromethoxy)phenyl]propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Example 27.

¹H NMR (400 MHz, CDCl₃) δ 0.97 (3H, t, J=3.9 Hz), 1.84-1.93 (2H, m),2.17 (3H, s), 4.69 (1H, d, J=3.9 Hz), 4.92 (1H, q, J=6.9 Hz), 5.19 (1H,s), 5.41 (1H, s), 7.18 (2H, d, J=7.8 Hz), 7.24 (1H, d, J=2.1 Hz),7.34-7.38 (2H, m), 8.11 (1H, d, J=2.1 Hz), 8.82 (1H, s), 10.41 (1H, d,J=7.5 Hz).

B)7-isopropyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Example 29.

MS (API+): [M+H]⁺ 437.2.

Example 376-chloro-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(6-chloro-3-nitropyridin-2-yl)glycinate

To a solution of methyl glycinate hydrochloride (15.0 g) and2,6-dichloro-3-nitropyridine (21.0 g) in ethanol (100 mL) was addedtriethylamine (30.9 mL). The reaction mixture was heated at reflexovernight, and the solvent was evaporated under reduced pressure. Theresidue was diluted with ethyl acetate, and the mixture was washedsuccessively with water and saturated brine, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (petroleum ether/ethyl acetate) to give thetitle compound (16.3 g).

¹H NMR (400 MHz, DMSO-d₆) δ 3.67 (3H, s), 4.26 (2H, d, J=5.6 Hz), 6.87(1H, d, J=8.8 Hz), 8.48 (1H, d, J=8.8 Hz), 8.98 (1H, t, J=5.2 Hz).

B) 6-chloro-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl N-(6-chloro-3-nitropyridin-2-yl)glycinate (13.3g) in ethanol (650 mL) was added tin(II) chloride dihydrate (98.0 g).The reaction mixture was heated at reflex overnight, and theprecipitated solid was collected by filtration, and dried under reducedpressure to give the title compound (9.4 g).

¹H NMR (400 MHz, DMSO-d₆) δ 3.95 (2H, s), 6.56 (1H, d, J=8.0 Hz), 6.91(1H, d, J=7.6 Hz), 7.22 (1H, s), 10.49 (1H, s).

C)6-chloro-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

The title compound was obtained in the same manner as in Step C ofExample 26.

¹H NMR (400 MHz, DMSO-d₆) δ 0.01 (9H, s), 0.90 (2H, t, J=8.4 Hz), 3.58(2H, t, J=8.0 Hz), 4.09 (2H, s), 5.29 (2H, s), 6.74 (1H, d, J=7.6 Hz),7.34 (1H, d, J=8.0 Hz), 7.39 (1H, brs).

D)6-chloro-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Under nitrogen atmosphere, to a solution of6-chloro-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(7.9 g) and triethylamine (7.63 g) in tetrahydrofuran (150 mL) wasslowly added triphosgene (5.98 g) at room temperature. The reactionmixture was stirred at 45° C. for 2 hr,1-(4-(trifluoromethoxy)phenyl)propan-1-amine hydrochloride (7.72 g) wasadded thereto, and the mixture was stirred at 60° C. for further 12 hr.The reaction mixture was concentrated under reduced pressure, and theobtained residue was purified by silica gel column chromatography(petroleum ether/ethyl acetate) to give the title compound (7.0 g).

¹H NMR (400 MHz, DMSO-d₆) δ 0.02 (9H, s), 0.90-1.01 (5H, m), 1.86-1.92(2H, m), 3.65 (2H, t, J=11.2 Hz), 4.68 (2H, t, J=6.4 Hz), 4.88-4.90 (1H,m), 5.30 (2H, d, J=4.0 Hz), 7.07 (1H, d, J=11.2 Hz), 7.19 (2H, d, J=10.8Hz), 7.35-7.39 (2H, m), 7.67 (1H, d, J=11.6 Hz), 9.80 (1H, d, J=9.2 Hz).

E)6-chloro-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step E ofExample 26.

MS (API+): [M+H]⁺ 429.1.

¹H NMR (300 MHz, CDCl₃) δ 0.97 (3H, t, J=7.2 Hz), 1.84-1.93 (2H, m),4.64 (2H, d, J=2.0 Hz), 4.85-4.90 (1H, m), 6.98 (1H, d, J=7.6 Hz),7.17-7.19 (3H, m), 7.36 (2H, d, J=8.4 Hz), 9.81 (1H, s), 9.96 (1H, d,J=7.2 Hz).

Example 38N-(1-(4-(1-methyl-1H-pyrazol-4-yl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step B ofExample 28.

MS (API+): [M+H]⁺ 391.2.

Example 392-oxo-N-(1-(4-(prop-1-en-2-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step B ofExample 28.

MS (API+): [M+H]⁺ 351.2.

Example 40N-(1-(4-isopropylphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of2-oxo-N-(1-(4-(prop-1-en-2-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(46 mg) in methanol (3 mL) was added palladium-carbon-ethylene diaminecomplex (15 mg). The reaction mixture was stirred at room temperaturefor 2 hr under hydrogen atmosphere, and the insoluble substance wasfiltered off. The filtrate was concentrated under reduced pressure, theresidue was dissolved in methanol (3 mL), and 10% palladium-carbon(containing 50% water, 15 mg) was added thereto. The reaction mixturewas stirred at room temperature for 2 hr under hydrogen atmosphere, theinsoluble substance was filtered off, and the filtrate was concentratedunder reduced pressure. The residue was purified by HPLC (C18, mobilephase: water/acetonitrile (containing 0.1% TFA)), to the obtainedfraction was added saturated aqueous sodium hydrogen carbonate solution,and the mixture was extracted with ethyl acetate. The extract was driedover anhydrous sodium sulfate, and concentrated under reduced pressureto give the title compound (22.0 mg).

MS (API+): [M+H]⁺ 353.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.85 (3H, t, J=7.3 Hz), 1.18 (6H, d, J=6.8Hz), 1.68-1.85 (2H, m), 2.75-2.94 (1H, m), 4.41 (2H, s), 4.73 (1H, q,J=7.0 Hz), 7.09 (1H, dd, J=7.9, 4.9 Hz), 7.15-7.25 (4H, m), 7.31 (1H,dd, J=7.9, 1.5 Hz), 8.01 (1H, dd, J=4.9, 1.5 Hz), 10.29 (1H, d, J=7.5Hz), 10.81 (1H, brs).

Example 41N-(1-(4-(3,6-dihydro-2H-pyran-4-yl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step B ofExample 28.

MS (API+): [M+H]⁺ 393.2.

Example 42N-(2-amino-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) amino(4-(trifluoromethoxy)phenyl)acetonitrile hydrochloride

4-(Trifluoromethoxy)benzaldehyde (10 g) was dissolved in 2 Mammonia/methanol solution (105 mL), and titanium(IV) tetraisopropoxide(15.4 mL) was added thereto under ice-cooling. The reaction mixture wasstirred at the same temperature for 10 min, trimethylsilanecarbonitrile(7.83 g) was added thereto, and the mixture was stirred overnight atroom temperature. Then, saturated aqueous sodium hydrogen carbonatesolution was added thereto, the insoluble substance was filtered offusing Celite, and the filtrate was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. To the residue was added 4 M hydrogenchloride/ethyl acetate solution (20 mL) under ice-cooling, and thesolvent was evaporated under reduced pressure to give the title compound(10.0 g).

MS (API+), found: 200.0.

¹H NMR (300 MHz, DMSO-d₆) δ 5.91-6.12 (1H, m), 7.47-7.62 (2H, m),7.74-7.95 (2H, m), 9.61 (3H, brs).

B) 2-amino-2-(4-(trifluoromethoxy)phenyl)acetamide

To a mixture of amino(4-(trifluoromethoxy)phenyl)acetonitrilehydrochloride (3 g), potassium carbonate (4.92 g) and dimethyl sulfoxide(30 mL) was added 35% aqueous hydrogen peroxide (3.12 mL) underice-cooling. The reaction mixture was stirred overnight at roomtemperature, saturated aqueous sodium thiosulfate solution was addedthereto, and the mixture was stirred at room temperature for further 5min. The reaction mixture was added to saturated brine, and the mixturewas extracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure to give the title compound (2.15 g).

MS (API+): [M+H]⁺ 235.1.

C)N-(2-amino-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 410.1.

¹H NMR (300 MHz, DMSO-d₆) δ 4.28-4.50 (2H, m), 5.45 (1H, d, J=6.8 Hz),7.12 (1H, dd, J=7.9, 4.9 Hz), 7.24-7.41 (4H, m), 7.51-7.60 (2H, m), 7.87(1H, s), 8.01 (1H, dd, J=4.9, 1.5 Hz), 10.66 (1H, d, J=6.8 Hz), 10.81(1H, s).

Example 43N-(cyano(4-(trifluoromethoxy)phenyl)methyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 392.1.

¹H NMR (300 MHz, DMSO-d₆) δ 4.46 (2H, s), 6.30 (1H, d, J=7.5 Hz), 7.13(1H, dd, J=7.9, 4.9 Hz), 7.33 (1H, dd, J=7.9, 1.5 Hz), 7.47 (2H, d,J=8.3 Hz), 7.64-7.74 (2H, m), 7.93-8.00 (1H, m), 10.67 (1H, d, J=7.5Hz), 10.86 (1H, s).

Example 447-cyano-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-7-carbonitrile

To a solution of7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(1.00 g), zinc cyanide (579 mg) and zinc (81 mg) inN,N-dimethylacetamide (10 mL) was added di-tert-butylphosphinepalladium(0) (126 mg). The reaction mixture was stirred overnight at110° C. under nitrogen atmosphere, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (petroleum ether/ethyl acetate) to give the titlecompound (598 mg).

¹H NMR (400 MHz, CDCl₃) δ 0.01 (9H, s), 0.97 (2H, t, J=10.8 Hz), 3.65(2H, t, J=11.0 Hz), 4.31 (2H, d, J=1.6 Hz), 5.34 (2H, s), 7.57 (1H, d,J=2.0 Hz), 8.14 (1H, s).

B)7-cyano-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step D ofExample 26.

¹H NMR (300 MHz, CDCl₃) δ 0.01 (9H, s), 0.91-1.00 (5H, m), 1.84-1.94(2H, m), 3.66 (2H, t, J=8.1 Hz), 4.66-4.79 (2H, m), 4.88 (1H, q, J=6.9Hz), 5.29-5.37 (2H, m), 7.19 (2H, d, J=8.1 Hz), 7.34 (2H, d, J=8.7 Hz),7.89 (1H, d, J=2.1 Hz) 8.34 (1H, d, J=1.8 Hz), 10.01 (1H, d, J=7.2 Hz).

C)7-cyano-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step E ofExample 26.

MS (API−): [M−H]⁻ 418.0.

¹H NMR (400 MHz, CDCl₃) δ 0.96 (3H, t, J=7.2 Hz), 1.85-1.92 (2H, m),4.65-4.75 (2H, m), 4.87 (1H, q, J=7.6 Hz), 7.17 (2H, d, J=8.0 Hz),7.31-7.34 (2H, m), 7.36 (1H, d, J=2.0 Hz), 8.29 (1H, d, J=2.0 Hz), 9.79(1H, s), 10.18 (1H, d, J=7.6 Hz).

Example 452-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-6-(trifluoromethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-nitroacetamide

An aqueous solution of nitroethyl acetate (45.0 g) in 28% ammonia (300mL) was stirred at room temperature for 24 hr, and the solvent wasevaporated under reduced pressure. To the residue was added water, thepH of the mixture was adjusted to 3 with 1 M hydrochloric acid, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure to give the title compound(35 g).

¹H NMR (400 MHz, DMSO-d₆) δ 5.28 (2H, s), 7.64 (1H, s), 7.86 (1H, s).

B) 3-nitro-6-(trifluoromethyl)pyridin-2-ol

To a solution of 2-nitroacetamide (16.9 g) and(3E)-4-ethoxy-1,1,1-trifluorobut-3-en-2-one (30.0 g) in ethanol (700 mL)was slowly added sodium ethoxide (22.1 g) at room temperature. Thereaction mixture was stirred at 90° C. for 2 hr, the pH of the mixturewas adjusted to 2 with 1 M hydrochloric acid, and the mixture wasstirred at room temperature for additional 30 min. To the reactionmixture was added water, and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure to give the title compound (5.5 g).

¹H NMR (400 MHz, CDCl₃) δ 7.46 (1H, d, J=8.0 Hz), 8.69 (1H, d, J=8.0Hz), 11.02 (1H, brs).

C) 2-chloro-3-nitro-6-(trifluoromethyl)pyridine

To 3-nitro-6-(trifluoromethyl)pyridin-2-ol (5.5 g) was added phosphorouspentachloride (25.0 g) at room temperature. The reaction mixture wasstirred at 170° C. for 2.5 hr, cooled to room temperature, and slowlypoured into ice-water. The mixture was extracted with ethyl acetate, andthe extract was washed successively with saturated brine and saturatedaqueous sodium hydrogen carbonate solution, and dried over anhydroussodium sulfate, and the solvent was evaporated under reduced pressure togive the title compound (5.0 g).

¹H NMR (300 MHz, CDCl₃) δ 7.84 (1H, d, J=8.1 Hz), 8.38 (1H, d, J=8.1Hz).

D) methyl N-(6-trifluoromethyl-3-nitropyridin-2-yl)glycinate

The title compound was obtained in the same manner as in Step A ofExample 1.

¹H NMR (300 MHz, CDCl₃) δ 3.81 (3H, s), 4.41 (2H, d, J=5.4 Hz), 7.07(1H, d, J=8.4 Hz), 8.53 (1H, brs), 8.62 (1H, d, J=8.4 Hz).

E) 6-(trifluoromethyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methylN-(6-trifluoromethyl-3-nitropyridin-2-yl)glycinate (3.37 g) in ethanol(75 mL) was added tin(II) chloride dihydrate (14.2 g). The reactionmixture was stirred at 80° C. for 2 hr, and the solvent was evaporatedunder reduced pressure. The residue was dissolved in ethyl acetate, thepH of the solution was adjusted to 9 with saturated aqueous ammoniasolution, and the insoluble substance was filtered off using Celite. Thefiltrate was concentrated under reduced pressure, and the obtainedresidue was purified by silica gel column chromatography (petroleumether/ethyl acetate) to give the title compound (1.04 g).

¹H NMR (400 MHz, CDCl₃+CD₃OD) δ 4.19 (2H, s), 6.97 (1H, d, J=7.6 Hz),7.02 (1H, d, J=7.6 Hz).

F)2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-6-(trifluoromethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step D ofExample 26.

MS (API+): [M+H]⁺ 463.1.

¹H NMR (400 MHz, CDCl₃) δ 0.95 (3H, t, J=7.2 Hz), 1.79-1.93 (2H, m),4.66-4.75 (2H, m), 4.85 (1H, q, J=7.2 Hz), 7.17 (2H, d, J=8.0 Hz), 7.28(1H, d, J=8.0 Hz), 7.32-7.36 (3H, m), 7.63 (1H, brs), 10.12 (1H, d,J=7.6 Hz).

Example 462-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-6-vinyl-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of6-chloro-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(1.10 g), 2-ethenyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (539 mg) and(1,1-bis(diphenylphosphino)ferrocene)dichloropalladium(II) (100 mg) in amixed solvent of 1,2-dimethoxyethane (15 mL) and water (5 mL) was addedcesium carbonate (1.67 g) at room temperature. The reaction mixture wasstirred at 120° C. for 4 hr under nitrogen atmosphere using microwave,water was added thereto, and the mixture was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (petroleum ether/ethyl acetate) to give thetitle compound (500 mg).

MS (API+): [M+H]⁺ 421.2.

¹H NMR (300 MHz, CDCl₃) δ 0.98 (3H, t, J=7.2 Hz), 1.84-1.94 (2H, m),4.70 (2H, s), 4.90 (1H, d, J=7.2 Hz), 5.41 (1H, d, J=10.8 Hz), 5.91 (1H,d, J=17.1 Hz), 6.68 (1H, dd, J=17.4, 7.8 Hz), 6.98 (1H, d, J=8.1 Hz),7.16-7.22 (3H, m), 7.37 (2H, d, J=8.4 Hz), 10.14 (1H, s), 10.54 (1H, d,J=7.2 Hz).

Example 476-benzyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of6-chloro-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(420 mg), 2-benzyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (181 mg) and(1,1-bis(diphenylphosphino)ferrocene)dichloropalladium(II) (50 mg) in amixed solvent of 1,2-dimethoxyethane (15 mL) and water (5 mL) was addedcesium carbonate (645 mg) at room temperature. The reaction mixture wasstirred at 100° C. for 40 min under nitrogen atmosphere using microwave,water was added thereto, and the mixture was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by HPLC(C18, mobile phase: water/acetonitrile (containing 0.1% TFA)), to theobtained fraction was added saturated aqueous sodium hydrogen carbonatesolution, and the mixture was extracted with ethyl acetate. The extractwas dried over anhydrous sodium sulfate, and concentrated under reducedpressure to give the title compound (100 mg).

MS (API+): [M+H]⁺ 485.2.

¹H NMR (300 MHz, CDCl₃) δ 0.88 (3H, t, J=7.2 Hz), 1.60-1.68 (2H, m),4.07 (2H, s), 4.65 (2H, s), 4.80 (1H, d, J L 7.2 Hz), 6.89 (1H, d, J=8.1Hz), 7.08-7.19 (8H, m), 7.25-7.34 (2H, m), 9.69 (1H, s), 10.34 (1H, d,J=7.5 Hz).

Example 482-oxo-N-(1-(4-(tetrahydro-2H-pyran-4-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution ofN-(1-(4-(3,6-dihydro-2H-pyran-4-yl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(42.5 mg) in methanol (3 mL) was added 10% palladium-carbon (containing50% water, 15 mg). The reaction mixture was stirred at room temperaturefor 4 hr under hydrogen atmosphere, the insoluble substance was filteredoff, and the filtrate was concentrated under reduced pressure. Theresidue was purified by HPLC (C18, mobile phase: water/acetonitrile(containing 0.1% TFA)), to the obtained fraction was added saturatedaqueous sodium hydrogen carbonate solution, and the mixture wasextracted with ethyl acetate. The extract was dried over anhydroussodium sulfate, and concentrated under reduced pressure to give thetitle compound (27.9 mg).

MS (API+): [M+H]⁺ 395.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.85 (3H, t, J=7.3 Hz), 1.52-1.86 (6H, m),2.62-2.82 (1H, m), 3.34-3.50 (2H, m), 3.86-4.00 (2H, m), 4.41 (2H, s),4.74 (1H, q, J=6.9 Hz), 7.09 (1H, dd, J=7.9, 4.9 Hz), 7.15-7.28 (4H, m),7.31 (1H, dd, J=7.7, 1.7 Hz), 8.01 (1H, dd, J=4.9, 1.5 Hz), 10.29 (1H,d, J=7.5 Hz), 10.80 (1H, brs).

Example 49N-(1-(6-methoxypyridin-3-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 6-methoxynicotinonitrile

To a solution of 6-chloronicotinonitrile (10.0 g) in methanol (100 mL)was added sodium methoxide (7.80 g). The reaction mixture was heated atreflux overnight, and the solvent was evaporated under reduced pressure.To the residue was added water, and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, and dried oversodium sulfate, and the solvent was evaporated under reduced pressure togive the title compound (8.8 g).

¹H NMR (400 MHz, DMSO-d₆) δ 4.00 (3H, s), 6.83 (1H, dd, J=8.8, 0.8 Hz),7.78 (1H, dd, J=8.6, 2.4 Hz), 8.50 (1H, d, J=1.4 Hz).

B) 6-methoxynicotine acid

To a solution of 6-methoxynicotinonitrile (5.00 g) in ethanol (100 mL)was added 2 M aqueous potassium hydroxide solution (20 mL). The reactionmixture was heated at reflex for 2 hr, and the solvent was evaporatedunder reduced pressure. To the residue was added water, the pH of themixture was adjusted to 4-5 with 2 M hydrochloric acid, and the mixturewas extracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure to give the title compound (4.2 g).

¹H NMR (400 MHz, DMSO-d₆) δ 3.92 (3H, s), 6.86-6.92 (1H, m), 8.11-8.15(1H, m), 8.73 (1H, d, J=2.0 Hz), 13.0 (1H, s).

C) N,6-dimethoxy-N-methylnicotinamide

To a solution of 6-methoxynicotine acid (4.2 g) and N-methoxymethylaminehydrochloride (3.8 g) in dichloromethane (100 mL) were added1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (7.6 g) and4-dimethylaminopyridine (0.32 g). The reaction mixture was stirred atroom temperature for 10 min, N,N-diisopropylethylamine (10.0 g) wasadded thereto, and the mixture was stirred overnight at roomtemperature. The reaction mixture was washed with saturated brine, anddried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (ethyl acetate/petroleum ether) to give the titlecompound (3.6 g).

¹H NMR (400 MHz, CDCl₃) δ 3.58 (3H, s), 3.77 (3H, s), 3.98 (3H, s),6.72-6.77 (1H, m), 7.97-8.00 (1H, m), 8.62-8.65 (1H, m).

D) 1-(6-methoxypyridin-3-yl)propan-1-one

To a solution of N,6-dimethoxy-N-methylnicotinamide (3.6 g) intetrahydrofuran (50 mL) was added 3 M ethylmagnesiumbromide/tetrahydrofuran solution (18 mL) at −40° C. The reaction mixturewas stirred at the same temperature for 2 hr, saturated aqueous ammoniumchloride solution was added thereto, and the mixture was extracted withethyl acetate. The extract was washed with saturated brine, and driedover anhydrous sodium sulfate, and the solvent was evaporated underreduced pressure to give the title compound (2.9 g).

¹H NMR (400 MHz, CDCl₃) δ 1.23 (3H, t, J=7.2 Hz), 2.95 (2H, q, J=7.2Hz), 4.00 (3H, s), 6.78 (1H, dd, J=8.4, 0.4 Hz), 8.15 (1H, dd, J=8.8,2.4 Hz), 8.80 (1H, d, J=2.4 Hz).

E) 1-(6-methoxypyridin-3-yl)propan-1-amine

To a solution of 1-(6-methoxypyridin-3-yl)propan-1-one (2.9 g) inethanol (50 mL) were added hydroxylamine hydrochloride (1.5 g) andtriethylamine (2.1 g). The reaction mixture was heated at refluxovernight, and the solvent was evaporated under reduced pressure. To theresidue was added water, and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. To a solution of the obtained solid (800 mg) in methanol (10mL) was added Raney nickel (160 mg). The reaction mixture was stirred at50° C. for 3 hr under hydrogen atmosphere (50 psi), the insolublesubstance was filtered off using Celite, and the filtrate wasconcentrated under reduced pressure to give the title compound (600 mg).

¹H NMR (400 MHz, DMSO-d₆) δ 0.76 (3H, t, J=7.6 Hz), 1.45-1.61 (2H, m),3.35 (2H, brs), 3.64-3.67 (1H, m), 3.81 (3H, s), 6.74 (1H, dd, J=13.6,8.4 Hz), 7.67 (1H, dd, J=8.4, 2.4 Hz), 8.03 (1H, dd, J=8.4, 2.0 Hz).

F)N-(1-(6-methoxypyridin-3-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of 1-(6-methoxypyridin-3-yl)propan-1-amine (100 mg) inN,N-dimethylformamide (10 mL) were added 4-nitrophenyl2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (223 mg) andtriethylamine (181 mg). The reaction mixture was stirred overnight atroom temperature, and the solvent was evaporated under reduced pressure.The residue was purified by HPLC (C18, mobile phase: water/acetonitrile(containing 0.1% TFA)), to the obtained fraction was added saturatedaqueous sodium hydrogen carbonate solution, and the mixture wasextracted with ethyl acetate. The extract was dried over anhydroussodium sulfate, and concentrated under reduced pressure to give thetitle compound (80 mg).

MS (API+): [M+H]⁺ 342.1.

¹H NMR (300 MHz, CDCl₃) δ 0.97 (3H, t, J=7.5 Hz), 1.83-1.95 (2H, m),3.92 (3H, s), 4.62-4.75 (2H, m), 4.87 (1H, q, d, J=7.2 Hz), 6.72 (1H, d,J=8.4 Hz), 6.99 (1H, dd, J=7.8, 5.1 Hz), 7.20 (1H, dd, J=7.8, 1.5 Hz),7.55 (1H, dd, J=8.7, 2.4 Hz), 8.00 (1H, dd, J=4.8, 1.5 Hz), 8.14 (1H, d,J=2.7 Hz), 9.16 (1H, s), 10.40 (1H, d, J=7.2 Hz).

Example 50N-(1-(5-methoxypyrimidin-2-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 5-methoxypyrimidine-2-carbonitrile

To a solution of 2-chloro-5-methoxypyrimidine (4.4 g) and1,4-diazabicyclo[2.2.2]octane (6.7 g) in a mixed solvent of dimethylsulfoxide (114 mL) and water (18 mL) was added potassium cyanide (4.00g). The reaction mixture was stirred at 70° C. for 5 hr, water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed with saturated brine, and dried over sodium sulfate, and thesolvent was evaporated under reduced pressure to give the title compound(3.5 g).

¹H NMR (400 MHz, CDCl₃) δ 4.02 (3H, s), 8.47 (2H, s).

B) 1-(5-methoxypyrimidin-2-yl)propan-1-one

The title compound was obtained in the same manner as in Step B ofExample 30.

¹H NMR (300 MHz, CDCl₃) δ 1.25 (3H, t, J=7.2 Hz), 3.23 (2H, q, J=7.2Hz), 4.02 (3H, s), 8.53 (2H, s).

C) N-benzyl-1-(5-methoxypyrimidin-2-yl)propan-1-amine

To a solution of 1-(5-methoxypyrimidin-2-yl)propan-1-one (500 mg) andbenzyl amine (308 mg) in 1,2-dichloroethane (10 mL) was added sodiumtriacetoxyborohydride (953.5 mg). The reaction mixture was stirredovernight at 25° C., dichloromethane was added thereto, and washed withsaturated brine. The organic layer was dried over anhydrous sodiumsulfate, and the solvent was evaporated under reduced pressure to givethe title compound (700 mg).

¹H NMR (300 MHz, CDCl₃) δ 0.85 (3H, t, J=7.5 Hz), 1.77-1.83 (2H, m),3.61 (2H, dd, J=15.3, 12.9 Hz), 3.82 (1H, t, J=6.6 Hz), 3.94 (3H, s),7.20-7.36 (5H, m), 8.40 (2H, s).

D) 1-(5-methoxypyrimidin-2-yl)propan-1-amine

To a solution of N-benzyl-1-(5-methoxypyrimidin-2-yl)propan-1-amine (700mg) in methanol (10 mL) was added 10% palladium-carbon (containing 50%water, 100 mg). The reaction mixture was stirred at room temperature for5 hr under hydrogen atmosphere (20 psi), the insoluble substance wasfiltered off, and the filtrate was concentrated under reduced pressureto give the title compound (500 mg).

¹H NMR (300 MHz, CDCl₃) δ 0.92 (3H, t, J=7.5 Hz), 1.69-1.79 (2H, m),3.94 (3H, s), 3.92-4.02 (1H, m), 8.38 (2H, s).

E)N-(1-(5-methoxypyrimidin-2-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 343.2.

¹H NMR (400 MHz, CDCl₃) δ 0.95 (3H, t, J=7.2 Hz), 1.96-2.09 (2H, m),3.91 (3H, s), 4.60 (2H, q, J=18.0 Hz), 5.17 (1H, q, J=6.8 Hz), 6.95-6.98(1H, dd, J=8.0, 4.8 Hz), 7.14 (1H, dd, J=7.6, 1.6 Hz), 8.03 (1H, dd,J=4.8, 1.6 Hz), 8.40 (2H, s), 9.46 (1H, s), 10.63 (1H, d, J=7.2 Hz).

Example 516-ethyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Example 29.

MS (API+): [M+H]⁺ 423.1.

¹H NMR (400 MHz, CDCl₃) δ 0.97 (3H, t, J=7.2 Hz), 1.27 (3H, t, J=7.6Hz), 1.83-1.93 (2H, m), 2.71-2.77 (2H, m), 4.66 (2H, s), 4.87-4.92 (1H,m), 6.82 (1H, d, J=7.6 Hz), 7.13-7.18 (3H, m), 7.33-7.37 (2H, m), 9.91(1H, s), 10.65 (1H, d, J=7.6 Hz).

Example 526-methoxy-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(6-methoxy-3-nitropyridin-2-yl)glycinate

To a solution of ethyl N-(6-chloro-3-nitropyridin-2-yl)glycinate (1.50g) in methanol (40 mL) was added sodium methoxide (469 mg). The reactionmixture was stirred at 70° C. for 2 hr, water was added thereto, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure to give the title compound(1.4 g).

¹H NMR (400 MHz, DMSO-d₆) δ 3.67 (3H, s), 3.84 (3H, s), 4.29 (2H, d,J=6.0 Hz), 6.22 (1H, t, J=4.4 Hz), 8.34 (1H, d, J=8.8 Hz), 9.11 (1H, s).

B)6-methoxy-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of methyl N-(6-methoxy-3-nitropyridin-2-yl)glycinate (1.40g) in ethanol (40 mL) was added tin(II) chloride dihydrate (8.00 g). Thereaction mixture was stirred overnight at 80° C., and the solvent wasevaporated under reduced pressure to give a crude product (9.4 g) of6-methoxy-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one. To a solution ofthe crude product (4.00 g) of6-methoxy-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one andN,N-diisopropylethylamine (10 mL) in tetrahydrofuran (100 mL) was slowlyadded triphosgene (602 mg) at room temperature. The reaction mixture wasstirred at 45° C. for 2 hr, and the solvent was evaporated under reducedpressure. The residue was dissolved in tetrahydrofuran (50 mL), and1-(4-(trifluoromethoxy)phenyl)propan-1-amine hydrochloride (602 mg) wasadded thereto. The mixture was stirred overnight at 65° C., and thesolvent was evaporated under reduced pressure. To the residue was addedwater, and the mixture was extracted with ethyl acetate. The extract waswashed with saturated brine, and dried over anhydrous sodium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by HPLC (C18, mobile phase: water/acetonitrile (containing 0.1%TFA)), to the obtained fraction was added saturated aqueous sodiumhydrogen carbonate solution, and the mixture was extracted with ethylacetate. The extract was dried over anhydrous sodium sulfate, andconcentrated under reduced pressure to give the title compound (90 mg).

MS (API+): [M+H]⁺ 425.1.

¹H NMR (400 MHz, CDCl₃) δ 0.97 (3H, t, J=7.6 Hz), 1.82-1.91 (2H, m),3.77 (3H, s), 4.56-4.68 (2H, m), 4.85-4.90 (1H, m), 6.46 (1H, d, J=8.4Hz), 7.16-7.22 (3H, m), 7.36 (2H, d, J=8.4 Hz), 9.61 (1H, d, J=7.2 Hz),9.64 (1H, s).

Example 53N-(1-(4-(cyclopropylmethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) tert-butyl(1-(4-(cyclopropylmethoxy)phenyl)propyl)carbamate

To a solution of tert-butyl(1-(4-hydroxyphenyl)propyl)carbamate (303mg), cyclopropylmethanol (104 mg) and tributylphosphine (394 mg) intetrahydrofuran (10 mL) was added 1,1′-(azodicarbonyl)dipiperidine (457mg). The reaction mixture was stirred at room temperature for 1 hr, andhexane was added thereto. The precipitated solid was filtered off, andthe filtrate was concentrated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (292 mg).

MS (API+): [M+H]⁺ 306.2.

B)N-(1-(4-(cyclopropylmethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of the hydrochloride (217 mg) (obtained fromtert-butyl(1-(4-(cyclopropylmethoxy)phenyl)propyl)carbamate (292 mg) inthe same manner as in Step E of Example 18) in N,N-dimethylacetamide (6mL) were added 4-nitrophenyl2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (282 mg) andtriethylamine (0.456 mL). The reaction mixture was stirred at roomtemperature for 16 hr, and the solvent was evaporated under reducedpressure. To the residue was added aqueous sodium hydrogen carbonatesolution, and the mixture was extracted with ethyl acetate. The extractwas washed with water, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The obtained solid wastriturated with ethyl acetate/methanol, collected by filtration, andwashed with ethyl acetate to give the title compound (136 mg).

MS (API+): [M+H]⁺ 381.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.20-0.37 (2H, m), 0.48-0.64 (2H, m), 0.83(3H, t, J=7.3 Hz), 1.09-1.32 (1H, m), 1.64-1.88 (2H, m), 3.77 (2H, d,J=6.8 Hz), 4.41 (2H, d, J=0.8 Hz), 4.70 (1H, q, J=7.0 Hz), 6.81-6.93(2H, m), 7.09 (1H, dd, J=7.9, 4.9 Hz), 7.14-7.24 (2H, m), 7.30 (1H, dd,J=7.9, 1.5 Hz), 7.99 (1H, dd, J=4.9, 1.5 Hz), 10.23 (1H, d, J=7.5 Hz),10.80 (1H, s).

Example 542-oxo-N-(1-(4-(trifluoromethyl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) N-hydroxy-1-(4-(trifluoromethyl)phenyl)propan-1-imine

The title compound was obtained in the same manner as in Step C ofExample 1.

¹H NMR (300 MHz, CDCl₃) δ 1.06-1.23 (3H, m), 2.54-2.90 (2H, m),7.47-7.78 (4H, m), 8.14-8.53 (1H, m).

B) 1-(4-(trifluoromethyl)phenyl)propan-1-amine

To a solution of N-hydroxy-1-(4-(trifluoromethyl)phenyl)propan-1-imine(2.15 g) in ethanol (100 mL) was added 20% palladium hydroxide-carbon(200 mg). The reaction mixture was stirred overnight at room temperatureunder hydrogen atmosphere, the reaction mixture was filtered, and thefiltrate was concentrated under reduced pressure. The residue waspurified by silica gel column chromatography (NH, hexane/ethyl acetate)to give the title compound (988 mg).

¹H NMR (300 MHz, CDCl₃) δ 0.87 (3H, t, J=7.3 Hz), 1.62-1.77 (2H, m),3.89 (1H, t, J=6.8 Hz), 7.44 (2H, d, J=7.9 Hz), 7.58 (2H, d, J=7.9 Hz).

C)2-oxo-N-(1-(4-(trifluoromethyl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 379.2.

¹H NMR (300 MHz, CDCl₃) δ 0.97 (3H, t, J=7.3 Hz), 1.89 (2H, quin, J=7.3Hz), 4.67 (2H, s), 4.93 (1H, q, J=6.8 Hz), 7.01 (1H, dd, J=7.7, 5.1 Hz),7.19 (1H, dd, J=7.5, 1.5 Hz), 7.44 (2H, d, J=8.3 Hz), 7.58 (2H, d, J=8.3Hz), 8.01 (1H, dd, J=4.9, 1.5 Hz), 9.16 (1H, brs), 10.48 (1H, d, J=7.2Hz).

Example 552-oxo-N-((pyridin-2-yl)(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) N-methoxy-N-methylpyridine-2-carboxamide

The title compound was obtained in the same manner as in Step A ofExample 31.

MS (API+): [M+H]⁺ 167.1.

B) pyridin-2-yl(4-(trifluoromethoxy)phenyl)methanone

To a solution of N-methoxy-N-methylpyridine-2-carboxamide (2.7 g) intetrahydrofuran (60 mL) was added 0.5 M(4-(trifluoromethoxy)phenylmagnesium bromide/tetrahydrofuran solution(32.5 mL) at room temperature. The reaction mixture was stirredovernight at room temperature, saturated aqueous ammonium chloridesolution was added thereto, and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (ethyl acetate/hexane) to give the title compound (2.69g).

MS (API+): [M+H]⁺ 268.0.

C) 1-(pyridin-2-yl)-1-(4-(trifluoromethoxy)phenyl)methanaminehydrochloride

The title compound was obtained in the same manner as in Steps C-E ofExample 1.

MS (API+): [M+H]⁺ 269.0.

D)2-oxo-N-((pyridin-2-yl)(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 444.2.

¹H NMR (300 MHz, CDCl₃) δ 4.53-4.74 (2H, m), 6.25 (1H, d, J=6.8 Hz),6.99 (1H, dd, J=7.9, 4.9 Hz), 7.09-7.25 (4H, m), 7.29 (1H, d, J=7.9 Hz),7.43-7.53 (2H, m), 7.66 (1H, td, J=7.7, 1.9 Hz), 8.08 (1H, dd, J=5.1,1.7 Hz), 8.64 (1H, dd, J=4.9, 0.8 Hz), 9.24 (1H, brs), 11.41 (1H, d,J=6.8 Hz).

Example 56N-((3,5-dimethyl-1,2-oxazol-4-yl)(4-(trifluoromethoxy)phenyl)methyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) (3,5-dimethyl-1,2-oxazol-4-yl)(4-(trifluoromethoxy)phenyl)methanone

The title compound was obtained in the same manner as in Step A ofExample 31 and Step B of Example 55.

MS (API+): [M+H]⁺ 286.0.

B)1-(3,5-dimethyl-1,2-oxazol-4-yl)-N-hydroxy-1-(4-(trifluoromethoxy)phenyl)methanimine

The title compound was obtained in the same manner as in Step C ofExample 1.

MS (API+): [M+H]⁺ 301.1.

C)1-(3,5-dimethyl-1,2-oxazol-4-yl)-1-(4-(trifluoromethoxy)phenyl)methanamine

To a solution of1-(3,5-dimethyl-1,2-oxazol-4-yl)-N-hydroxy-1-(4-(trifluoromethoxy)phenyl)methanimine(460 mg) in tetrahydrofuran (15 mL) was added 1.1 Mborane-tetrahydrofuran complex/tetrahydrofuran solution (4.18 mL) atroom temperature. The reaction mixture was stirred overnight at 80° C.under nitrogen atmosphere, 1 M hydrochloric acid was added thereto, andthe mixture was stirred at room temperature for 15 min. Then, to thereaction mixture was added saturated aqueous sodium hydrogen carbonatesolution, and the mixture was extracted with ethyl acetate. The extractwas washed successively with saturated aqueous sodium hydrogen carbonatesolution and saturated brine, and dried over anhydrous magnesiumsulfate, and the solvent was evaporated under reduced pressure to givethe title compound (398 mg).

MS (API+), found: 270.1.

D)N-((3,5-dimethyl-1,2-oxazol-4-yl)(4-(trifluoromethoxy)phenyl)methyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 462.1.

¹H NMR (300 MHz, CDCl₃) δ 2.12 (3H, s), 2.38 (3H, s), 4.62-4.83 (2H, m),6.25 (1H, d, J=8.3 Hz), 7.02 (1H, dd, J=7.7, 5.1 Hz), 7.15-7.23 (3H, m),7.27-7.36 (2H, m), 7.91 (1H, dd, J=5.1, 1.3 Hz), 8.38 (1H, brs), 10.79(1H, d, J=8.3 Hz).

Example 57N-((1-methyl-1H-pyrazol-4-yl)(4-(trifluoromethoxy)phenyl)methyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step A ofExample 31, Step B of Example 55, Steps C-E of Example 1 and Step G ofExample 7.

MS (API+): [M+H]⁺ 447.2.

¹H NMR (300 MHz, CDCl₃) δ 3.86 (3H, s), 4.60-4.77 (2H, m), 6.18 (1H, d,J=7.2 Hz), 6.99 (1H, dd, J=7.7, 5.1 Hz), 7.08-7.24 (4H, m), 7.33-7.48(3H, m), 7.94 (1H, d, J=4.9 Hz), 9.00 (1H, brs), 10.68 (1H, d, J=7.5Hz).

Example 58N-(2-(dimethylamino)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) tert-butyl(cyano(4-(trifluoromethoxy)phenyl)methyl)carbamate

To a solution of amino(4-(trifluoromethoxy)phenyl)acetonitrilehydrochloride (3 g) and triethylamine (3.31 mL) in tetrahydrofuran (50mL) was added di-tert-butyl dicarbonate (3.03 mL) at room temperature.The reaction mixture was stirred overnight at room temperature, furtherdi-tert-butyl dicarbonate (500 mg) was added at room temperature, andthe mixture was stirred for 2 days. The reaction mixture was filteredthrough silica gel pad, and eluted with ethyl acetate. The filtrate wasconcentrated under reduced pressure to give the title compound (4.14 g).

¹H NMR (300 MHz, CDCl₃) δ 1.49 (9H, s), 5.01-5.24 (1H, m), 5.82 (1H,brs), 7.22-7.34 (2H, m), 7.49-7.60 (2H, m).

B) tert-butyl(2-amino-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate

To a solution of cobalt(II) chloride (328 mg) andtert-butyl(cyano(4-(trifluoromethoxy)phenyl)methyl)carbamate (400 mg) inmethanol (8 mL) was added sodium borohydride (478 mg) under ice-cooling.The reaction mixture was stirred for 40 min under ice-cooling, 1 Mhydrochloric acid (10 mL) was added thereto, and the mixture was stirredat room temperature for 10 min. To the reaction mixture was added 8 Maqueous sodium hydroxide solution (5 mL), the insoluble substance wasfiltered off using Celite, and the filtrate was extracted with ethylacetate. The extract was washed with saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure to give the title compound (360 mg).

MS (API+): [M+H]⁺ 321.1.

C) tert-butyl(2-(dimethylamino)-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate

To a solution oftert-butyl(2-amino-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate (180mg) and 37% aqueous formaldehyde solution (109 mg) in methanol (5 mL)was added borane-2-picoline complex (180 mg) under ice-cooling. Thereaction mixture was stirred overnight at room temperature undernitrogen atmosphere, 1 M hydrochloric acid (5 mL) was added thereto atroom temperature, and the mixture was stirred at the same temperaturefor 10 min. The reaction mixture was neutralized with saturated aqueoussodium hydrogen carbonate solution, and extracted with ethyl acetate.The extract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure to give the title compound (118 mg).

MS (API+): [M+H]⁺ 349.1.

D) N²,N²-dimethyl-1-(4-(trifluoromethoxy)phenyl)ethane-1,2-diaminedihydrochloride

Totert-butyl(2-(dimethylamino)-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate(117 mg) was added 4 M hydrogen chloride/ethyl acetate solution (5 mL).The reaction mixture was stirred at room temperature for 10 min, and thesolvent was evaporated under reduced pressure to give the title compound(128 mg).

MS (API+), found: 249.1.

E)N-(2-(dimethylamino)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 424.1.

¹H NMR (300 MHz, DMSO-d₆) δ 2.20 (6H, s), 2.35-2.78 (2H, m), 4.29-4.52(2H, m), 4.89 (1H, brs), 7.10 (1H, dd, J=7.5, 4.9 Hz), 7.25-7.35 (3H,m), 7.45 (2H, d, J=8.3 Hz), 7.99 (1H, dd, J=4.9, 1.9 Hz), 10.38 (1H, d,J=6.0 Hz), 10.81 (1H, s).

Example 59N-(2-(methylsulfanyl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-(methylsulfanyl)-1-(4-(trifluoromethoxy)phenyl)ethanone

To a solution of 2-bromo-1-(4-(trifluoromethoxy)phenyl)ethanone (5 g) intetrahydrofuran (150 mL) was added sodium thiomethoxide (1.24 g) underice-cooling. The reaction mixture was stirred at room temperature for 1hr, filtered through NH silica gel pad, and eluted with ethylacetate/hexane. The filtrate was concentrated under reduced pressure togive the title compound (4.23 g).

¹H NMR (300 MHz, CDCl₃) δ 2.14 (3H, s), 3.74 (2H, s), 7.27-7.36 (2H, m),7.99-8.10 (2H, m).

B) 2-(methylsulfanyl)-1-(4-(trifluoromethoxy)phenyl)ethanamine

The title compound was obtained in the same manner as in Step C ofExample 1 and Step C of Example 56.

MS (API+), found: 235.0.

C)N-(2-(methylsulfanyl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺ 427.1.

¹H NMR (300 MHz, CDCl₃) δ 2.05 (3H, s), 2.97 (2H, d, J=6.0 Hz), 4.69(2H, s), 5.24 (1H, q, J=6.4 Hz), 7.01 (1H, dd, J=7.7, 5.1 Hz), 7.12-7.25(3H, m), 7.34-7.46 (2H, m), 8.03 (1H, dd, J=4.9, 1.5 Hz), 9.55 (1H,brs), 10.76 (1H, d, J=7.2 Hz).

Example 60N-(2-(methylsulfonyl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution ofN-(2-(methylsulfanyl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(54.0 mg) in ethyl acetate (10 mL) was added 3-chloroperbenzoic acid(68.7 mg) at room temperature. The reaction mixture was stirredovernight at room temperature, saturated aqueous sodium thiosulfatesolution was added thereto, and the mixture was stirred for 5 min. Then,to the reaction mixture was added saturated aqueous sodium hydrogencarbonate solution, and the mixture was extracted with ethyl acetate.The extract was washed successively with saturated aqueous sodiumhydrogen carbonate solution and saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The obtained solid was triturated with hexane/ethylacetate, collected by filtration, and washed with hexane/ethyl acetateto give the title compound (38.2 mg).

MS (API+): [M+H]⁺ 459.2.

¹H NMR (300 MHz, DMSO-d₆) δ 2.91 (3H, s), 3.63 (1H, dd, J=14.7, 4.5 Hz),4.00 (1H, dd, J=14.5, 9.2 Hz), 4.26-4.56 (2H, m), 5.46 (1H, td, J=8.5,3.8 Hz), 7.11 (1H, dd, J=7.9, 4.9 Hz), 7.30 (1H, dd, J=7.9, 1.5 Hz),7.33-7.41 (2H, m), 7.53-7.61 (2H, m), 7.98 (1H, dd, J=4.9, 1.5 Hz),10.62 (1H, d, J=7.9 Hz), 10.82 (1H, s).

Example 61N-(1-(5-methoxypyridin-2-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl 5-methoxypyridine-2-carboxylate

To a solution of 2-bromo-5-methoxypyridine (21 g) and triethylamine (55g) in a mixed solvent of N,N-dimethylformamide (100 mL) and methanol(100 mL) were added 1,3-bis(diphenylphosphino)-propane (7.0 g) andpalladium(II) acetate (3.6 g). The reaction mixture was stirred at 100°C. for 24 hr under carbon monoxide atmosphere (5.0 MPa), and dilutedwith ethyl acetate, and the mixture was washed with saturated brine. Theorganic layer was dried over anhydrous sodium sulfate, and the solventwas evaporated under reduced pressure. The residue was purified bysilica gel column chromatography (petroleum ether/ethyl acetate) to givethe title compound (10.2 g).

¹H NMR (300 MHz, CDCl₃) δ 3.93 (3H, s), 3.99 (3H, s), 7.25-7.29 (1H, m),8.12 (1H, d, J=8.4 Hz), 8.40 (1H, d, J=3.0 Hz).

B) 5-methoxypyridine-2-carboxylic acid

To a solution of methyl 5-methoxypyridine-2-carboxylate (4.0 g) inmethanol (50 mL) was added a solution of lithium hydroxide monohydrate(5.0 g) in water (10 mL). The reaction mixture was stirred at roomtemperature for 12 hr, the pH of the mixture was adjusted to 4-5 with 2M hydrochloric acid, and the precipitate was collected by filtration.The obtained solid was washed with water, and dried to give the titlecompound (2.4 g).

¹H NMR (400 MHz, DMSO-d₆) δ 3.93 (3H, s), 7.49-7.51 (1H, m), 8.03 (1H,d, J=7.2 Hz), 8.36 (1H, d, J=2.8 Hz), 12.85 (1H, s).

C)N-(1-(5-methoxypyridin-2-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Steps C-E ofExample 49 and Step G of Example 7.

MS (API+): [M+H]⁺ 342.1.

¹H NMR (400 MHz, CDCl₃) δ 0.79 (3H, t, J=7.2 Hz), 1.77-1.85 (2H, m),3.81 (3H, s), 4.43 (2H, s), 4.82 (1H, q, J=6.8 Hz), 7.09 (1H, dd, J=8.0,5.2 Hz), 7.28-7.36 (3H, m), 8.00 (1H, d, J=4.0 Hz), 8.26 (1H, d, J=2.8Hz), 10.35 (1H, d, J=7.6 Hz).

Example 626-cyano-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)6-cyano-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of6-chloro-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(1.00 g), zinc cyanide (126 mg) and zinc (200 mg) inN,N-dimethylformamide (10 mL) were addedtris(dibenzylideneacetone)dipalladium(0) (100 mg) and1,1′-bis(diphenylphosphino)ferrocene (100 mg). The reaction mixture wasstirred at 120° C. for 6 hr under nitrogen atmosphere, water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed with saturated brine, and dried over anhydrous sodiumsulfate, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (petroleumether/ethyl acetate) to give the title compound (320 mg).

¹H NMR (300 MHz, CDCl₃) δ 0.00 (9H, s), 0.92-1.00 (5H, m), 1.84-1.98(2H, m), 3.61-3.67 (2H, m), 4.66-4.78 (2H, m), 4.85-4.90 (1H, m),5.30-5.38 (2H, m), 7.20 (2H, d, J=8.4 Hz), 7.36 (2H, d, J=8.8 Hz), 7.46(1H, d, J=8.4 Hz), 7.74 (1H, d, J=8.4 Hz), 9.82 (1H, d, J=7.6 Hz).

B)6-cyano-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To6-cyano-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(320 mg) was added trifluoroacetic acid (3 mL) at room temperature. Thereaction mixture was stirred at room temperature for 2 hr, and thesolvent was evaporated under reduced pressure. To the residue was addedaqueous sodium hydrogen carbonate solution, and the mixture wasextracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by HPLC(C18, mobile phase: water/acetonitrile (containing 0.1% TFA)), to theobtained fraction was added saturated aqueous sodium hydrogen carbonatesolution, and the mixture was extracted with ethyl acetate. The extractwas dried over anhydrous sodium sulfate, and concentrated under reducedpressure to give the title compound (110 mg).

MS (API−): [M−H]⁻ 418.2.

¹H NMR (400 MHz, DMSO-d₆) δ 0.94 (3H, t, J=7.2 Hz), 1.76-1.84 (2H, m),4.34-4.43 (2H, m), 4.80-4.85 (2H, m), 7.31-7.36 (3H, m), 7.48 (2H, d,J=8.4 Hz), 7.71 (1H, d, J=8.0 Hz), 9.59 (1H, d, J=7.2 Hz), 11.27 (1H,s).

Example 637-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate

To a solution of 2-chloro-5-iodo-3-nitropyridine (12.0 g) in ethanol(200 mL) were added methyl glycinate hydrochloride (10.6 g) andtriethylamine (11.8 mL) at room temperature. The reaction mixture washeated at reflux for 20 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue wascrystallized from hexane/ethyl acetate to give the title compound (11.1g).

MS (API+): [M+H]⁺ 338.0.

B) 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate (6.00 g)in tetrahydrofuran (300 mL) was added 5% platinum-carbon (500 mg). Thereaction mixture was stirred overnight at room temperature underhydrogen atmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure. The residue was dissolved inethanol (200 mL), the solution was heated at reflux for 16 hr, and thesolvent was evaporated under reduced pressure. The residue was washedwith diisopropyl ether to give the title compound (4.48 g).

MS (API+): [M+H]⁺ 276.0.

C)7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a suspension of 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(3.82 g) in N,N-dimethylformamide (160 mL) was slowly added 1 Mpotassium hexamethyldisilazide/tetrahydrofuran solution (17.4 mL) at 0°C. The reaction mixture was stirred at 0° C. for 1 hr,2-(chloromethoxy)ethyltrimethylsilane (3.62 mL) was slowly addedthereto, and the mixture was stirred at room temperature for 20 hr. Tothe reaction mixture was added water, the insoluble substance wasfiltered off using Celite, and the filtrate was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (NH, hexane/ethyl acetate) to give the titlecompound (2.71 g).

MS (API+): [M+H]⁺ 406.0.

D) 2-methoxy-1-(4-(trifluoromethoxy)phenyl) ethanone

To a solution of 2-bromo-1-(4-(trifluoromethoxy)phenyl)ethanone (6.12 g)in methanol (150 mL) were added silver(I) carbonate (7.75 g) and borontrifluoride diethyl ether complex (3.29 mL) at room temperature. Thereaction mixture was stirred at 50° C. for 20 hr, the insolublesubstance was filtered off, and the filtrate was concentrated underreduced pressure. To the residue was added water, and the mixture wasextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (4.78 g).

MS (API+): [M+H]⁺ 235.1.

E) 2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethanamine hydrochloride

To a solution of 2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethanone (4.78g) in ethanol (120 mL) were added hydroxylamine hydrochloride (2.84 g)and triethylamine (5.69 mL) at room temperature. The reaction mixturewas stirred at room temperature for 5.5 hr, and the solvent wasevaporated under reduced pressure. To the residue was added water, andthe mixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reduced pressureto give a crude product ofN-hydroxy-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethanimine. To asolution of the obtained crude product in ethanol (160 mL) was added 10%palladium-carbon (containing 50% water, 350 mg). The reaction mixturewas stirred at room temperature for 16 hr under hydrogen atmosphere, thecatalyst was filtered off, and the filtrate was concentrated underreduced pressure. To a solution of the residue in ethyl acetate (10 mL)was added 4 M hydrogen chloride/ethyl acetate solution (100 mL), themixture was stirred at room temperature for 2 hr, and the solvent wasevaporated under reduced pressure. The residue was washed withdiisopropyl ether to give the title compound (4.2 g).

¹H NMR (300 MHz, DMSO-d₆) δ 3.34 (3H, s), 3.58-3.74 (2H, m), 4.58 (1H,dd, J=6.6, 5.5 Hz), 7.46 (2H, d, J=8.7 Hz), 7.65 (2H, d, J=8.3 Hz), 8.57(3H, brs).

F)7-iodo-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(1.11 g) in tetrahydrofuran (42.0 mL) was added a solution ofbis(trichloromethyl)carbonate (647 mg) in tetrahydrofuran (6.30 mL) atroom temperature under nitrogen atmosphere. The reaction mixture wasstirred at 40° C. for 1 hr under nitrogen atmosphere, and the solventwas evaporated under reduced pressure. To the residue was addedtetrahydrofuran, and the solvent was evaporated under reduced pressure.The operation (addition of tetrahydrofuran and then evaporation) wasrepeated three times. The residue was diluted with tetrahydrofuran (21.0mL), and the mixture was added to a mixture of2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethanamine hydrochloride (889mg) and triethylamine (1.15 mL) in tetrahydrofuran (14.0 mL) at roomtemperature. The reaction mixture was stirred overnight at 60° C., andthe solvent was evaporated under reduced pressure. To the residue wasadded ethyl acetate, washed successively with water and saturated brine,and dried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gelchromatography (hexane/ethyl acetate) to give the title compound (1.17g).

MS (API+): [M+H]⁺ 667.1.

G)7-hydroxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-iodo-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(100 mg), 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi-1,3,2-dioxaborolane(79.0 mg) and potassium acetate (60.7 mg) in N,N-dimethylformamide (1.50mL) was added (1,1-bis(diphenylphosphino)ferrocene)dichloropalladium(II)(11.2 mg). The reaction mixture was stirred overnight at 80° C. underargon atmosphere, water was added thereto, and the mixture was extractedwith ethyl acetate. The extract was washed with saturated brine, anddried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure to give a crude product (100 mg) ofN-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide.To a solution of the obtained crude product (100 mg) in tetrahydrofuran(1.50 mL) was added 2 M aqueous sodium hydroxide solution (0.300 mL) at0° C. The reaction mixture was stirred at 0° C. for 30 min, and 35%aqueous hydrogen peroxide (53.0 μL) was added thereto. The reactionmixture was stirred at room temperature for 1.5 hr, ice water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed successively with water and saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel chromatography(hexane/ethyl acetate) to give the title compound (43.3 mg).

MS (API+): [M+H]⁺ 557.2.

H)7-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-hydroxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(43.3 mg) in N,N-dimethylformamide (1.00 mL) were added potassiumcarbonate (10.8 mg) and iodomethane (7.33 μL). The reaction mixture wasstirred overnight at room temperature, water was added thereto, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel chromatography (hexane/ethyl acetate) to give the titlecompound (28.6 mg).

MS (API+):[M+H]⁺ 571.2.

I)7-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To7-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(28.6 mg) were added trifluoroacetic acid (0.710 mL) and water (79.5μL). The reaction mixture was stirred at room temperature for 3 hr, andthe solvent was evaporated under reduced pressure. The residue wasdissolved in N,N-dimethylformamide (1.35 mL), and 8 M ammonia/methanolsolution (270 μL) was added thereto. The reaction mixture was stirred atroom temperature for 2 hr, and the solvent was evaporated under reducedpressure. The residue was diluted with ethyl acetate, and the mixturewas washed successively with water and saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. The residue was washed with hexane/ethyl acetate to give thetitle compound (18.8 mg).

MS (API+): [M+H]⁺ 441.2.

¹H NMR (300 MHz, DMSO-d₆) δ 3.28 (3H, s), 3.54-3.68 (2H, m), 3.83 (3H,s), 4.30-4.49 (2H, m), 4.98-5.11 (1H, m), 6.96 (1H, d, J=2.6 Hz),7.28-7.36 (2H, m), 7.40-7.52 (2H, m), 7.76 (1H, d, J=2.6 Hz), 10.02 (1H,d, J=7.5 Hz), 10.76 (1H, brs).

Example 647-methoxy-N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(200 mg) was resolved by SFC (column: CHIRALPAK IA, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140), and crystallized from hexane/ethyl acetate togive the title compound having a shorter retention time (78.3 mg).

MS (API+): [M+H]⁺ 441.2.

¹H NMR (300 MHz, DMSO-d₆) δ 3.28 (3H, s), 3.52-3.70 (2H, m), 3.83 (3H,s), 4.26-4.52 (2H, m), 4.97-5.13 (1H, m), 6.96 (1H, d, J=2.6 Hz), 7.32(2H, d, J=8.3 Hz), 7.46 (2H, d, J=8.7 Hz), 7.76 (1H, d, J=2.6 Hz), 10.02(1H, d, J=7.5 Hz), 10.77 (1H, brs).

Example 657-methoxy-N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(200 mg) was resolved by SFC (column: CHIRALPAK IA, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140), and crystallized from hexane/ethyl acetate togive the title compound having a longer retention time (60.0 mg).

MS (API+): [M+H]⁺ 441.2.

¹H NMR (300 MHz, DMSO-d₆) δ 3.28 (3H, s), 3.53-3.67 (2H, m), 3.83 (3H,s), 4.27-4.51 (2H, m), 4.96-5.16 (1H, m), 6.96 (1H, d, J=3.0 Hz), 7.32(2H, d, J=8.3 Hz), 7.41-7.54 (2H, m), 7.76 (1H, d, J=2.6 Hz), 10.02 (1H,d, J=7.2 Hz), 10.76 (1H, brs).

Example 66N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate

To a solution of 2-chloro-5-iodo-3-nitropyridine (12.0 g) in ethanol(200 mL) were added methyl glycinate hydrochloride (10.6 g) andtriethylamine (11.8 mL) at room temperature. The reaction mixture washeated at reflux for 20 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue wascrystallized from hexane/ethyl acetate to give the title compound (11.1g).

MS (API+): [M+H]⁺ 338.0.

B) 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate (6.00 g)in tetrahydrofuran (300 mL) was added 5% platinum-carbon (500 mg). Thereaction mixture was stirred overnight at room temperature underhydrogen atmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure. The residue was dissolved inethanol (200 mL), the solution was heated at reflux for 16 hr, and thesolvent was evaporated under reduced pressure. The residue was washedwith diisopropyl ether to give the title compound (4.48 g).

MS (API+): [M+H]⁺ 276.0.

C)7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a suspension of 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(3.82 g) in N,N-dimethylformamide (160 mL) was slowly added 1 Mpotassium hexamethyldisilazide/tetrahydrofuran solution (17.4 mL) at 0°C. The reaction mixture was stirred at 0° C. for 1 hr,2-(chloromethoxy)ethyltrimethylsilane (3.62 mL) was slowly addedthereto, and the mixture was stirred at room temperature for 20 hr. Tothe reaction mixture was added water, the insoluble substance wasfiltered off using Celite, and the filtrate was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (NH, hexane/ethyl acetate) to give the titlecompound (2.71 g).

MS (API+): [M+H]⁺ 406.0.

D) 3-fluoro-N-methoxy-N-methyl-4-(trifluoromethoxy)benzamide

To a solution of 3-fluoro-4-(trifluoromethoxy)benzoic acid (20.0 g),N,O-dimethylhydroxylamine hydrochloride (10.5 g) and triethylamine (24.9mL) in N,N-dimethylformamide (300 mL) were added 1-hydroxybenzotriazolemonohydrate (16.4 g) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimidehydrochloride (20.5 g) at room temperature. The reaction mixture wasstirred overnight at room temperature, saturated aqueous sodium hydrogencarbonate solution was added thereto, and the mixture was extracted withethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure to give the title compound(22.9 g).

¹H NMR (300 MHz, CDCl₃) δ 3.38 (3H, s), 3.56 (3H, s), 7.30-7.42 (1H, m),7.51-7.65 (2H, m).

E) 1-(3-fluoro-4-(trifluoromethoxy)phenyl)ethanone

To a solution of3-fluoro-N-methoxy-N-methyl-4-(trifluoromethoxy)benzamide (3.52 g) intetrahydrofuran (60 mL) was slowly added 1 M methylmagnesiumbromide/tetrahydrofuran solution (39.5 mL) at 0° C. The reaction mixturewas stirred at room temperature for 4 hr, and poured into saturatedaqueous ammonium chloride solution, and the mixture was extracted withethyl acetate. The extract was dried over anhydrous sodium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (2.33 g).

¹H NMR (300 MHz, DMSO-d₆) δ 2.62 (3H, s), 7.68-7.80 (1H, m), 7.86-7.96(1H, m), 8.04 (1H, dd, J=11.0, 2.1 Hz).

F) 2-bromo-1-(3-fluoro-4-(trifluoromethoxy)phenyl)ethanone

To a solution of 1-(3-fluoro-4-(trifluoromethoxy)phenyl)ethanone (4.51g) in acetic acid (50 mL) was slowly added a solution of bromine (1.12mL) in acetic acid (5 mL) at room temperature. The reaction mixture wasstirred at 50° C. for 1.5 hr, and the solvent was evaporated underreduced pressure. Aqueous sodium hydrogen carbonate solution was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed with saturated aqueous sodium hydrogen carbonate solution,dried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (6.01g).

¹H NMR (300 MHz, DMSO-d₆) δ 4.99 (2H, s), 7.73-7.84 (1H, m), 7.92-8.00(1H, m), 8.12 (1H, dd, J=11.0, 2.0 Hz).

G) 1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethanone

To a solution of 2-bromo-1-(3-fluoro-4-(trifluoromethoxy)phenyl)ethanone(6.01 g) in methanol (60 mL) were added silver(I) carbonate (7.53 g) andboron trifluoride diethyl ether complex (3.10 mL). The reaction mixturewas stirred at 60° C. for 4 hr under nitrogen atmosphere, and theinsoluble substance was filtered off, and washed with ethyl acetate. Thefiltrate was concentrated under reduced pressure, and to the residuewere added ethyl acetate and brine. The precipitated solid was filteredoff, and the organic layer and aqueous layer of the filtrate wereseparated. The aqueous layer was extracted with ethyl acetate. Theextract was dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (hexane/ethyl acetate) to give the titlecompound (3.57 g).

¹H NMR (300 MHz, DMSO-d₆) δ 3.36 (3H, s), 4.81 (2H, s), 7.70-7.81 (1H,m), 7.83-7.92 (1H, m), 8.01 (1H, dd, J=10.9, 2.3 Hz).

H) 1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethanaminehydrochloride

To a mixture of1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethanone (3.57 g) andhydroxylamine hydrochloride (2.01 g) in ethanol (50 mL) was addedtriethylamine (3.99 mL). The reaction mixture was stirred at roomtemperature for 16 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed with saturated brine, anddried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure to give a crude product (3.89 g) of1-(3-fluoro-4-(trifluoromethoxy)phenyl)-N-hydroxy-2-methoxyethanimine.To a solution of the obtained crude product (3.89 g) in ethanol (60 mL)was added 20% palladium hydroxide-carbon (1.00 g). The reaction mixturewas stirred at room temperature for 5 hr under hydrogen atmosphere, theinsoluble substance was filtered off, and the filtrate was concentratedunder reduced pressure. The residue was dissolved in ethyl acetate (10mL), and 4 M hydrogen chloride/ethyl acetate solution (10 mL) was addedthereto. The solvent was evaporated under reduced pressure, and theprecipitated solid was washed with diisopropyl ether to give the titlecompound (2.86 g).

¹H NMR (300 MHz, DMSO-d₆) δ 3.32 (3H, s), 3.60-3.78 (2H, m), 4.53-4.66(1H, m), 7.46-7.55 (1H, m), 7.62-7.84 (2H, m), 8.70 (3H, brs).

I)N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-iodo-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(1.00 g) in tetrahydrofuran (37.4 mL) was slowly added a solution ofbis(trichloromethyl)carbonate (586 mg) in tetrahydrofuran (5.60 mL) atroom temperature under nitrogen atmosphere. The reaction mixture wasstirred at 40° C. for 3 hr under nitrogen atmosphere, and the solventwas evaporated under reduced pressure. To the residue was addedtetrahydrofuran, and the solvent was evaporated under reduced pressure.The operation (addition of tetrahydrofuran and then evaporation) wasrepeated three times. The residue was diluted with tetrahydrofuran (18.7mL), and the mixture was slowly added to a mixture of1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethanaminehydrochloride (858 mg) and triethylamine (1.04 mL) in tetrahydrofuran(12.4 mL) at room temperature. The reaction mixture was stirredovernight at 60° C., and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed with saturated brine, anddried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gelchromatography (hexane/ethyl acetate) to give the title compound (1.58g).

MS (API+): [M+H]⁺ 685.1.

J)N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-hydroxy-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution ofN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-iodo-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(1.58 g), 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi-1,3,2-dioxaborolane(1.19 g) and potassium acetate (935 mg) in N,N-dimethylformamide (23.1mL) was added (1,1-bis(diphenylphosphino)ferrocene)dichloropalladium(II)(173 mg). The reaction mixture was stirred overnight at 80° C. underargon atmosphere, water was added thereto, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure to give a crude product(2.02 g) ofN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide.To a solution of the obtained crude product (2.02 g) in tetrahydrofuran(29.6 mL) was added 2 M aqueous sodium hydroxide solution (5.91 mL) at0° C. The reaction mixture was stirred at 0° C. for 30 min, and 35%aqueous hydrogen peroxide (1.04 mL) was added thereto. The reactionmixture was stirred at room temperature for 2 hr, and ice water wasadded thereto. The mixture was acidified with 1 M hydrochloric acid, andextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous sodium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel chromatography (hexane/ethyl acetate) to give thetitle compound (1.24 g).

MS (API+):[M+H]⁺ 575.2.

K)N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution ofN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-hydroxy-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(1.24 g) in N,N-dimethylformamide (27.7 mL) were added potassiumcarbonate (300 mg) and iodomethane (204 μL). The reaction mixture wasstirred at room temperature for 3 hr, water was added thereto, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel chromatography (hexane/ethyl acetate) to give the titlecompound (646 mg).

MS (API+): [M+H]⁺ 589.2.

L)N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

ToN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(646 mg) were added trifluoroacetic acid (15.8 mL) and water (1.77 mL).The reaction mixture was stirred at room temperature for 1 hr, and thesolvent was evaporated under reduced pressure. The residue was dissolvedin N,N-dimethylformamide (30.1 mL), and 8 M ammonia/methanol solution(5.91 mL) was added thereto. The reaction mixture was stirred at roomtemperature for 2 hr, and the solvent was evaporated under reducedpressure. The residue was diluted with ethyl acetate, and the mixturewas washed successively with water and saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. The obtained solid was washed with hexane/ethyl acetate togive the title compound (402 mg).

MS (API+): [M+H]⁺ 459.1.

¹H NMR (300 MHz, DMSO-d₆) δ 3.29 (3H, s), 3.54-3.70 (2H, m), 3.83 (3H,s), 4.29-4.49 (2H, m), 5.00-5.13 (1H, m), 6.97 (1H, d, J=2.6 Hz), 7.29(1H, d, J=8.7 Hz), 7.41-7.59 (2H, m), 7.75 (1H, d, J=2.6 Hz), 10.01 (1H,d, J=7.5 Hz), 10.76 (1H, brs).

Example 67-IN-((1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(388 mg) was resolved by SFC (column: CHIRALPAK IA, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140), and crystallized from hexane/ethyl acetate togive the title compound having a shorter retention time (139 mg) ascrystals.

MS (API+): [M+H]⁺ 459.1.

¹H NMR (300 MHz, DMSO-d₆) δ 3.29 (3H, s), 3.55-3.70 (2H, m), 3.83 (3H,s), 4.28-4.51 (2H, m), 4.99-5.14 (1H, m), 6.97 (1H, d, J=3.0 Hz), 7.29(1H, d, J=8.7 Hz), 7.41-7.59 (2H, m), 7.75 (1H, d, J=2.6 Hz), 10.02 (1H,d, J=7.5 Hz), 10.76 (1H, brs).

Example 67-IIN-((1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) ethyl(5-bromopyridin-3-yl)carbamate

To a mixture of 5-bromopyridin-3-amine (35.4 g) and pyridine (19.8 mL)in tetrahydrofuran (600 mL) was slowly added ethyl chloroformate (23.4mL) at 0° C. The reaction mixture was stirred overnight at roomtemperature under nitrogen atmosphere, and poured into water, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. To the residue was addeddiisopropyl ether (400 mL), the mixture was stirred at room temperaturefor 20 min, and the obtained solid was collected by filtration to givethe title compound (29.0 g).

MS (API+):[M+H]⁺ 245.1.

B) ethyl(5-bromo-2-nitropyridin-3-yl) carbamate

To a solution of ethyl(5-bromopyridin-3-yl)carbamate (19.0 g) in conc.sulfuric acid (37.2 mL) was slowly added fuming nitric acid (26.1 mL) at0° C. The reaction mixture was stirred at room temperature for 72 hrunder nitrogen atmosphere. The reaction mixture was slowly poured intoice, the pH of the mixture was adjusted to 9 with 28% aqueous ammonia,and the mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. To the residue was addedethyl acetate/hexane, the mixture was stirred for 15 min, and theresulting solid was collected by filtration, and washed with hexane togive the title compound (13.9 g).

MS (API+):[M+H]⁺ 290.1.

C) 5-methoxy-2-nitropyridin-3-amine

To a solution of ethyl(5-bromo-2-nitropyridin-3-yl)carbamate (31.1 g) inmethanol (900 mL) was added 28% sodium methoxide/methanol solution (83.0g) at room temperature. The reaction mixture was stirred at 65° C. for 4hr under nitrogen atmosphere, and the solvent was evaporated to about150 mL under reduced pressure. To the residue was added saturatedaqueous ammonium chloride solution, the mixture was stirred at roomtemperature for 20 min, and the solvent was evaporated to about 100 mLunder reduced pressure. The resulting solid was collected by filtration,and washed with water to give the title compound (16.6 g).

MS (API+): [M+H]⁺ 170.2.

D) 2-chloro-N-(5-methoxy-2-nitropyridin-3-yl)acetamide

To a solution of 5-methoxy-2-nitropyridin-3-amine (24.7 g) inN,N-dimethylformamide (740 mL) was slowly added chloroacetyl chloride(23.2 mL) in tetrahydrofuran (40 mL) solution at 0° C. The reactionmixture was stirred at room temperature for 3 hr under nitrogenatmosphere, and the solvent was evaporated under reduced pressure. Tothe residue was added saturated aqueous sodium hydrogen carbonatesolution, and the mixture was extracted with ethyl acetate. The extractwas washed with saturated brine, and dried over anhydrous magnesiumsulfate, and the solvent was evaporated under reduced pressure. To theresidue was added diisopropyl ether/hexane, and the mixture was stirredat room temperature for 30 min. The obtained solid was collected byfiltration, and washed with diisopropyl ether/hexane to give the titlecompound (34.1 g).

MS (API+): [M+H]⁺ 246.0.

E) N-(2-amino-5-methoxypyridin-3-yl)-2-chloroacetamide

A mixture of 2-chloro-N-(5-methoxy-2-nitropyridin-3-yl)acetamide (34.1g), ammonium chloride (44.6 g), iron (27.1 g), ethanol (823 mL) andwater (206 mL) was stirred 75° C. for 40 min, and the solvent wasevaporated under reduced pressure. To the residue were addedtetrahydrofuran (500 mL) and saturated aqueous sodium hydrogen carbonatesolution (300 mL), and the reaction mixture was stirred for 15 min. Theinsoluble substance was filtered off through Celite, and to the filtratewas added saturated brine, and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, and the solventwas evaporated under reduced pressure. To the residue was addeddiisopropyl ether/hexane, and the obtained solid was collected byfiltration, and washed with diisopropyl ether/hexane to give the titlecompound (26.3 g).

MS (API+): [M+H]⁺ 216.1.

F) benzyl(3-((chloroacetyl)amino)-5-methoxypyridin-2-yl)carbamate

To a mixture of N-(2-amino-5-methoxypyridin-3-yl)-2-chloroacetamide(2.74 g) and pyridine (5.14 mL) in tetrahydrofuran (85 mL) was slowlyadded benzyl chloroformate (2.72 mL) at 0° C. The reaction mixture wasstirred at room temperature for 1 hr, ethyl acetate was added thereto,and the mixture was washed with a mixture of aqueous sodium hydrogencarbonate solution and brine. The organic layer was again washed withsaturated brine, and the solvent was evaporated under reduced pressure.The residue was purified by silica gel column chromatography(hexane/ethyl acetate), and the obtained solid was washed withdiisopropyl ether to give the title compound (3.79 g).

¹H NMR (300 MHz, DMSO-d₆) δ 3.82 (3H, s), 4.36 (2H, s), 5.13 (2H, s),7.30-7.43 (5H, m), 7.87 (1H, d, J=3.0 Hz), 7.95 (1H, d, J=2.6 Hz), 9.46(1H, s), 9.64 (1H, s).

G) benzyl7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate

To a solution ofbenzyl(3-((chloroacetyl)amino)-5-methoxypyridin-2-yl)carbamate (200 mg)in N,N-dimethylformamide (11 mL) was added cesium carbonate (279 mg) atroom temperature, and reaction mixture was stirred at 50° C. for 30 min.The reaction mixture was diluted with ethyl acetate, and washed withsaturated brine, and the solvent was evaporated under reduced pressure.The residue was purified by silica gel column chromatography(hexane/ethyl acetate) to give the title compound (115 mg).

¹H NMR (300 MHz, DMSO-d₆) δ 3.81 (3H, s), 4.36 (2H, s), 5.20 (2H, s),6.92 (1H, d, J=2.6 Hz), 7.27-7.43 (5H, m), 7.84 (1H, d, J=2.6 Hz), 10.72(1H, s).

H) 7-methoxy-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of benzyl7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate(0.722 g) in tetrahydrofuran (46.1 mL) was added 10% palladium-carbon(containing 50% water, 0.049 g), and the reaction mixture was stirred atroom temperature for 15 hr under hydrogen atmosphere. To the reactionmixture was added methanol at 50° C. to dissolve the precipitated solid,the catalyst was filtered off, and the filtrate was concentrated underreduced pressure. The obtained solid was washed with diisopropyl etherto give the title compound (0.380 g).

¹H NMR (300 MHz, DMSO-d₆) δ 3.68 (3H, s), 3.82 (2H, d, J=1.9 Hz), 6.32(1H, s), 6.66 (1H, d, J=2.6 Hz), 7.37 (1H, d, J=2.6 Hz), 10.32 (1H, s).

I) N, 2-dimethoxy-N-methylacetamide

To a mixture of N,O-dimethylhydroxylamine hydrochloride (24.7 g) andpotassium carbonate (63.7 g) in acetonitrile (330 mL) was added2-methoxyacetyl chloride (25.0 g) at the temperature of 10° C. or lower.The reaction mixture was stirred overnight at room temperature, theinsoluble substance was filtered off, and the filtrate was concentratedunder reduced pressure. The residue was distilled (boiling point: 60°C./0.8 KPa) to give the title compound (25.8 g).

¹H NMR (300 MHz, CDCl₃) δ 3.20 (3H, s), 3.47 (3H, d, J=0.8 Hz), 3.69(3H, s), 4.22 (2H, s).

J) 1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethanone

To a mixture of 4-bromo-2-fluoro-1-(trifluoromethoxy)benzene (25.0 g)and N,2-dimethoxy-N-methylacetamide (15.4 g) in tetrahydrofuran (400 mL)was slowly added 1.6 M n-butyllithium/hexane solution (72.4 mL) at −78°C. under nitrogen atmosphere. The reaction mixture was stirred at −78°C. for 20 min under nitrogen atmosphere, and neutralized with 0.1 Mhydrochloric acid, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gelchromatography (hexane/ethyl acetate) to give the title compound (15.7g).

¹H NMR (300 MHz, CDCl₃) δ 3.50 (3H, s), 4.63 (2H, s), 7.42 (1H, ddd,J=8.6, 7.3, 1.5 Hz), 7.75-7.81 (1H, m), 7.83 (1H, dd, J=10.2, 1.9 Hz).

K) 1-(3-fluoro-4-(trifluoromethoxy)phenyl)-N-hydroxy-2-methoxyethanimine

To a solution of1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethanone (7.56 g) inethanol (250 mL) were added hydroxylamine hydrochloride (4.17 g) andtriethylamine (8.36 mL) at room temperature. The reaction mixture wasstirred at room temperature for 16 hr, and the solvent was evaporatedunder reduced pressure. To the residue was added water, and the mixturewas extracted with ethyl acetate. The extract was washed successivelywith water and saturated brine, and dried over anhydrous magnesiumsulfate, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel chromatography (hexane/ethyl acetate)to give the title compound (7.88 g).

MS (API+): [M+H]⁺ 268.0.

L)tert-butyl(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)carbamate

To a solution of1-(3-fluoro-4-(trifluoromethoxy)phenyl)-N-hydroxy-2-methoxyethanimine(7.88 g) in ethanol (200 mL) was added 10% palladium-carbon (containing50% water, 1.00 g). The reaction mixture was stirred overnight at roomtemperature under hydrogen atmosphere, the insoluble substance wasfiltered off, and the filtrate was concentrated under reduced pressure.To a tetrahydrofuran solution (200 mL) of the residue were addeddi-tert-butyl dicarbonate (7.53 mL) and triethylamine (6.17 mL), and themixture was stirred at room temperature for 16 hr. To the reactionmixture was added water, and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (8.25g).

¹H NMR (300 MHz, CDCl₃) δ 1.42 (9H, brs), 3.35 (3H, s), 3.49-3.67 (2H,m), 4.78 (1H, brs), 5.34 (1H, brs), 7.08-7.29 (3H, m).

M)tert-butyl((1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)carbamate

Racemictert-butyl(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)carbamate(12.48 g) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=950/50) to give the title compound having a shorterretention time (5.73 g).

MS (API+), found: 254.0.

N) (1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethanaminehydrochloride

A mixture oftert-butyl((1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)carbamate(5.73 g) and 4 M hydrogen chloride/ethyl acetate solution (100 mL) wasstirred at room temperature for 3 hr. The solvent was evaporated underreduced pressure, and the residue was washed with diisopropyl ether togive the title compound (3.22 g).

MS (API+), found: 254.0.

O)N-((1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a mixture of 7-methoxy-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(2.49 g) and N,N-diisopropylethylamine (7.13 mL) in tetrahydrofuran (120mL) was slowly added 4-nitrophenyl chloroformate (3.64 g) at 0° C. Thereaction mixture was stirred at room temperature for 3 hr under nitrogenatmosphere, and the solvent was evaporated under reduced pressure. Tothe residue were added diisopropyl ether (200 mL) and saturated brine(150 mL), and the mixture was stirred at room temperature for 20 min.The resulting solid was collected by filtration, washed with water anddiisopropyl ether to give 4-nitrophenyl7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (4.20g). A mixture of 4-nitrophenyl7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (4.20g), N,N-diisopropylethylamine (11.9 mL) and(S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethanaminehydrochloride (4.43 g) in N,N-dimethylformamide (130 mL) was stirred atroom temperature for 16 hr, and the solvent was evaporated under reducedpressure. To the residue was added aqueous sodium hydrogen carbonatesolution, and the mixture was extracted with a mixed solvent of ethylacetate and tetrahydrofuran. The extract was washed with saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel chromatography (NH, hexane/ethyl acetate) to give(S)—N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(5.01 g). To a solution of the obtained(S)—N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(5.00 g) in ethanol (200 mL) was added activated carbon (shirasagi) (10g), and the mixture was stirred at room temperature for 30 min. Theinsoluble substance was filtered off, and washed with acetone. Thefiltrate was concentrated under reduced pressure to give(S)—N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(4.17 g). To a solution of the obtained(S)—N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(4.17 g) in acetone (35 mL) was slowly added heptane (70 mL) at 52° C.The mixture was stirred at 52° C. for 1 hr, heptane (35 mL) was slowlyadded thereto at 52° C., and the mixture was gradually cooled to roomtemperature. The mixture was stirred overnight at room temperature, andthen at 5° C. for 1 hr. The resulting solid was collected by filtration,and washed with acetone/heptane to give the title compound (3.15 g) ascrystals.

MS (API+): [M+H]⁺ 459.2.

¹H NMR (300 MHz, DMSO-d₆) δ 3.29 (3H, s), 3.56-3.70 (2H, m), 3.83 (3H,s), 4.30-4.52 (2H, m), 4.95-5.16 (1H, m), 6.96 (1H,d, J=2.6 Hz), 7.29(1H, d, J=8.3 Hz), 7.43-7.57 (2H, m), 7.75 (1H, d, J=3.0 Hz), 10.02 (1H,d, J=7.2 Hz), 10.78 (1H, brs).

Example 68N-((1R)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(388 mg) was resolved by SFC (column: CHIRALPAK IA, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140) to give the title compound having a longerretention time (145 mg).

MS (API+): [M+H]⁺ 459.1.

¹H NMR (300 MHz, DMSO-d₆) δ 3.29 (3H, s), 3.57-3.69 (2H, m), 3.83 (3H,s), 4.29-4.50 (2H, m), 4.97-5.15 (1H, m), 6.97 (1H, d, J=2.6 Hz), 7.29(1H, d, J=8.7 Hz), 7.41-7.59 (2H, m), 7.75 (1H, d, J=2.6 Hz), 10.02 (1H,d, J=7.5 Hz), 10.76 (1H, brs).

Example 697-methoxy-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate

To a solution of 2-chloro-5-iodo-3-nitropyridine (12.0 g) in ethanol(200 mL) were added methyl glycinate hydrochloride (10.6 g) andtriethylamine (11.8 mL) at room temperature. The reaction mixture washeated at reflux for 20 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue wascrystallized from hexane/ethyl acetate to give the title compound (11.1g).

MS (API+): [M+H]⁺ 338.0.

B) 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate (6.00 g)in tetrahydrofuran (300 mL) was added 5% platinum-carbon (500 mg). Thereaction mixture was stirred overnight at room temperature underhydrogen atmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure. The residue was dissolved inethanol (200 mL), the mixture was heated at reflux for 16 hr, and thesolvent was evaporated under reduced pressure. The residue was washedwith diisopropyl ether to give the title compound (4.48 g).

MS (API+):[M+H]⁺ 276.0.

C)7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a suspension of 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(3.82 g) in N,N-dimethylformamide (160 mL) was slowly added 1 Mpotassium hexamethyldisilazide/tetrahydrofuran solution (17.4 mL) at 0°C. The reaction mixture was stirred at 0° C. for 1 hr,2-(chloromethoxy)ethyltrimethylsilane (3.62 mL) was slowly addedthereto, and the mixture was stirred at room temperature for 20 hr. Tothe reaction mixture was added water, the insoluble substance wasfiltered off using Celite, and the filtrate was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (NH, hexane/ethyl acetate) to give the titlecompound (2.71 g).

MS (API+): [M+H]⁺ 406.0.

D) 2-methoxy-1-(4-(trifluoromethyl)phenyl)ethanone

To a solution of 2-bromo-1-(4-(trifluoromethyl)phenyl)ethanone (2.50 g)in methanol (50 mL) were added silver(I) carbonate (2.99 g) and borontrifluoride diethyl ether complex (1.42 mL) at room temperature. Thereaction mixture was stirred overnight at 50° C., the insolublesubstance was filtered off, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (1.84 g).

¹H NMR (300 MHz, CDCl₃) δ 3.51 (3H, s), 4.70 (2H, s), 7.75 (2H, d, J=8.3Hz), 8.06 (2H, d, J=7.9 Hz).

E) 2-methoxy-1-(4-(trifluoromethyl)phenyl)ethanamine hydrochloride

To a solution of 2-methoxy-1-(4-(trifluoromethyl)phenyl)ethanone (1.84g) in ethanol (100 mL) were added hydroxylamine hydrochloride (1.17 g)and triethylamine (2.35 mL) at room temperature. The reaction mixturewas stirred at room temperature for 4.5 hr, and the solvent wasevaporated under reduced pressure. To the residue was added water, andthe mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous magnesium sulfate, andthe solvent was evaporated under reduced pressure to give a crudeproduct of N-hydroxy-2-methoxy-1-(4-(trifluoromethyl)phenyl)ethanimine.To a solution of the obtained crude product in ethanol (100 mL) wasadded 10% palladium-carbon (containing 50% water, 200 mg). The reactionmixture was stirred overnight at room temperature under hydrogenatmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure. A solution of the residue in ethylacetate (5 mL) was added to 4 M hydrogen chloride/ethyl acetate solution(20 mL). The reaction mixture was stirred at room temperature for 30min, and the solvent was evaporated under reduced pressure. The residuewas crystallized from ethyl acetate to give the title compound (1.81 g).

¹H NMR (300 MHz, DMSO-d₆) δ 3.26-3.41 (3H, m), 3.59-3.78 (2H, m),4.58-4.73 (1H, m), 7.66-7.91 (4H, m), 8.69 (3H, brs).

F)7-iodo-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(1.53 g) in tetrahydrofuran (60 mL) was added a solution ofbis(trichloromethyl)carbonate (0.896 g) in tetrahydrofuran (8.0 mL) atroom temperature. The reaction mixture was stirred at 40° C. for 5 hr,and the solvent was evaporated under reduced pressure. The residue wasdiluted with tetrahydrofuran (10.0 mL), and the mixture was added to amixture of 2-methoxy-1-(4-(trifluoromethyl)phenyl)ethanaminehydrochloride (1.16 g) and triethylamine (1.58 mL) in tetrahydrofuran(60 mL) at room temperature. The reaction mixture was stirred at 60° C.for 16 hr, water was added thereto, and the mixture was extracted withethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (NH, hexane/ethyl acetate) to givethe title compound (2.18 g).

MS (API+): [M+H]⁺ 651.1.

G)7-hydroxy-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-iodo-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(1.19 g), 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi-1,3,2-dioxaborolane(941 mg), potassium acetate (742 mg) in N,N-dimethylformamide (18.3 mL)was added (1,1-bis(diphenylphosphino)ferrocene)dichloropalladium(II)(137 mg). The reaction mixture was stirred overnight at 80° C. underargon atmosphere, water was added thereto, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure to give a crude product(1.95 g) ofN-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-7-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide.To a solution of the obtained crude product (1.19 g) in tetrahydrofuran(18.3 mL) was added 2 M aqueous sodium hydroxide solution (3.67 mL) at0° C. The reaction mixture was stirred at 0° C. for 30 min, and 35%aqueous hydrogen peroxide (642 μL) was added thereto. The reactionmixture was stirred at room temperature for 2 hr, ice water was addedthereto, the mixture was acidified with 1 M hydrochloric acid, andextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous sodium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel chromatography (hexane/ethyl acetate) to give thetitle compound (796 mg).

MS (API+): [M+H]⁺ 541.2.

H)7-methoxy-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-hydroxy-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(796 mg) in N,N-dimethylformamide (18.9 mL) were added potassiumcarbonate (205 mg) and iodomethane (139 μL). The reaction mixture wasstirred overnight at room temperature, water was added thereto, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel chromatography (hexane/ethyl acetate) to give the titlecompound (665 mg).

MS (API+):[M+H]⁺ 555.2.

I)7-methoxy-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To7-methoxy-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide (665mg) were added trifluoroacetic acid (17.3 mL) and water (1.93 mL). Thereaction mixture was stirred at room temperature for 1 hr, and thesolvent was evaporated under reduced pressure. The residue was dissolvedin N,N-dimethylformamide (32.9 mL), and 8 M ammonia/methanol solution(6.46 mL) was added thereto. The reaction mixture was stirred at roomtemperature for 10 min, and the solvent was evaporated under reducedpressure. The residue was diluted with ethyl acetate, and the mixturewas washed successively with water and saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. The residue was crystallized from hexane/ethyl acetate to givethe title compound (474 mg).

MS (API+): [M+H]⁺ 425.1.

¹H NMR (300 MHz, DMSO-d₆) δ 3.28 (3H, s), 3.59-3.68 (2H, m), 3.83 (3H,s), 4.25-4.55 (2H, m), 5.00-5.17 (1H, m), 6.97 (1H, d, J=3.0 Hz), 7.56(2H, d, J=8.3 Hz), 7.64-7.73 (2H, m), 7.77 (1H, d, J=2.6 Hz), 10.07 (1H,d, J=7.5 Hz), 10.77 (1H, s).

Example 70 Optically active7-methoxy-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-methoxy-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(444 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=600/400), and crystallized from hexane/ethyl acetate togive the title compound having a shorter retention time (197 mg).

MS (API+): [M+H]⁺ 425.1.

¹H NMR (300 MHz, DMSO-d₆) δ 3.28 (3H, s), 3.61-3.68 (2H, m), 3.83 (3H,s), 4.29-4.50 (2H, m), 5.03-5.16 (1H, m), 6.97 (1H, d, J=2.6 Hz), 7.56(2H, d, J=8.3 Hz), 7.69 (2H, d, J=8.3 Hz), 7.77 (1H, d, J=2.6 Hz), 10.07(1H, d, J=7.2 Hz), 10.77 (1H, brs).

Example 71 Optically active7-methoxy-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-methoxy-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(444 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=600/400), and crystallized from hexane/ethyl acetate togive the title compound having a longer retention time (189 mg).

MS (API+): [M+H]⁺ 425.1.

¹H NMR (300 MHz, DMSO-d₆) δ 3.28 (3H, s), 3.61-3.67 (2H, m), 3.83 (3H,s), 4.30-4.50 (2H, m), 5.04-5.16 (1H, m), 6.97 (1H, d, J=2.6 Hz), 7.56(2H, d, J=8.3 Hz), 7.69 (2H, d, J=8.3 Hz), 7.77 (1H, d, J=2.6 Hz), 10.07(1H, d, J=7.5 Hz), 10.77 (1H, s).

Example 72-I7-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate

To a solution of 2-chloro-5-iodo-3-nitropyridine (12.0 g) in ethanol(200 mL) were added methyl glycinate hydrochloride (10.6 g) andtriethylamine (11.8 mL) at room temperature. The reaction mixture washeated at reflux for 20 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue wascrystallized from hexane/ethyl acetate to give the title compound (11.1g).

MS (API+): [M+H]⁺ 338.0.

B) methyl N-(5-cyclopropyl-3-nitropyridin-2-yl)glycinate

A mixture of methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate (1.00 g),cyclopropylboronic acid (0.510 g), palladium(II) acetate (0.100 g),tricyclohexylphosphine (0.250 g) and tripotassium phosphate (1.89 g) intoluene (30 mL) was stirred at 90° C. for 16 hr under argon atmosphere,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (0.130 g).

MS (API+): [M+H]⁺ 252.1.

C) 7-cyclopropyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a mixture of methyl N-(5-cyclopropyl-3-nitropyridin-2-yl)glycinate(73 mg) in a mixed solvent of ethanol (10 mL) and tetrahydrofuran (2 mL)was added 10% palladium-carbon (containing 50% water, 10 mg). Thereaction mixture was stirred at room temperature for 2.5 hr underhydrogen atmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure. The residue (64 mg) was dissolvedin ethanol (8 mL), the reaction mixture was heated at reflux for 16 hr,and the solvent was evaporated under reduced pressure. The residue waswashed with ethyl acetate to give the title compound (39.9 mg).

MS (API+): [M+H]⁺ 190.1.

D) 5-cyclopropyl-3-nitropyridin-2-amine

A mixture of 5-bromo-3-nitropyridin-2-amine (2.27 g), cyclopropylboronicacid (1.79 g), palladium(II) acetate (0.117 g), tricyclohexylphosphine(0.292 g), tripotassium phosphate (5.53 g), toluene (30 mL),1,2-dimethoxyethane (10 mL) and water (10 mL) was stirred overnight at100° C. under nitrogen atmosphere, and the insoluble substance wasfiltered off using Celite. The filtrate was washed successively withwater and saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (2.04 g).

MS (API+): [M+H]⁺180.2.

E) 7-cyclopropylpyrido[2,3-b]pyrazin-2(1H)-one

To a solution of 5-cyclopropyl-3-nitropyridin-2-amine (6.89 g) inethanol (300 mL) was added 10% palladium-carbon (containing 50% water,1.64 g). The reaction mixture was stirred at room temperature for 5 hrunder hydrogen atmosphere, the catalyst was filtered off, and thefiltrate was concentrated under reduced pressure. The residue wassuspended in water (150 mL), 9 M aqueous glyoxylic acid solution (6.41mL) was added thereto at room temperature. The reaction mixture wasstirred overnight at room temperature, and the resulting solid wascollected by filtration, and washed with water and diisopropyl ether togive the title compound (4.52 g).

F) 7-cyclopropyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of 7-cyclopropylpyrido[2,3-b]pyrazin-2(1H)-one (4.52 g) inethanol (150 mL) was added sodium borohydride (1.83 g) at roomtemperature. The reaction mixture was stirred at 32° C. for 1 hr, andconcentrated to about half of the volume under reduced pressure. To theresidue was added water, and the resulting solid was collected byfiltration, and washed with diisopropyl ether to give the title compound(3.45 g).

MS (API+): [M+H]⁺190.2.

G) 7-cyclopropyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of 7-cyclopropylpyrido[2,3-b]pyrazin-2(1H)-one (40.0 mg)in methanol (30 mL) was added 20% palladium hydroxide-carbon (15.0 mg).The reaction mixture was stirred at room temperature for 2 hr underhydrogen atmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure to give the title compound (30.0mg).

MS (API+): [M+H]⁺190.2.

H) 4-nitrophenyl7-cyclopropyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate

To a mixture of 7-cyclopropyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(35.0 mg) in a mixed solvent of N,N-dimethylacetamide (1.5 mL) andpyridine (0.3 mL) was added 4-nitrophenyl chloroformate (44.7 mg). Thereaction mixture was stirred at room temperature for 2 hr, water wasadded thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with 1 M hydrochloric acid, water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue wascrystallized from hexane/ethyl acetate to give the title compound (24.0mg).

MS (API+): [M+H]⁺ 355.1.

I) methyl2-((tert-butoxycarbonyl)amino)-2-(4-(trifluoromethoxy)phenyl)acetate

To a mixture of 4-(trifluoromethoxy)benzaldehyde (19.0 g) and ammoniumcarbonate (25.9 g) in a mixed solvent of ethanol (114 mL) and water(45.6 mL) was slowly added an aqueous solution (71.1 mL) of potassiumcyanide (8.14 g) at 50° C. The reaction mixture was stirred at 60° C.for 3 hr, and cooled to room temperature, and the ethanol was evaporatedunder reduced pressure. The pH of the residue was adjusted to 1 withconc. hydrochloric acid at 0° C., and the resulting solid was filteredoff, and washed with water. To an aqueous solution (100 mL) of potassiumhydroxide (23.6 g) was added the solid obtained by the above-mentionedoperation at room temperature, and the reaction mixture was stirred at90° C. for 3 days. The reaction mixture was cooled to room temperature,and neutralized with conc. hydrochloric acid. The resulting solid wasfiltered off, and washed with water to give a crude product (13.3 g) of2-amino-2-(4-(trifluoromethoxy)phenyl)acetic acid. To a solution of theobtained crude product (13.3 g) in tetrahydrofuran (113 mL) were addeddi-tert-butyl dicarbonate (19.7 mL) and 2 M aqueous sodium hydroxidesolution (85 mL) at room temperature. The reaction mixture was stirredovernight at room temperature, and poured into water, and the mixturewas washed with diethyl ether. The pH of the aqueous layer was adjustedto 3 with 1 M hydrochloric acid at 0° C., and the mixture was extractedwith ethyl acetate. The extract was washed with saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure to give a crude product (11.3 g) of2-((tert-butoxycarbonyl)amino)-2-(4-(trifluoromethoxy)phenyl)aceticacid. To a solution of the obtained crude product (11.3 g) inN,N-dimethylformamide (84 mL) were added methyl iodide (2.53 mL) andpotassium carbonate (5.59 g) at room temperature. The reaction mixturewas stirred at room temperature for 2 hr, and poured into water, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (8.20 g).

MS (API−): [M−H]⁻ 348.1.

J)tert-butyl(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate

To a solution of methyl2-((tert-butoxycarbonyl)amino)-2-(4-(trifluoromethoxy)phenyl)acetate(5.00 g) in tetrahydrofuran (71.6 mL) was slowly added 1 Mmethylmagnesium bromide/tetrahydrofuran solution (57.3 mL) at 0° C. Thereaction mixture was stirred at 0° C. for 1 hr under argon atmosphere,saturated aqueous ammonium chloride solution was added thereto at 0° C.,and the mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous magnesium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (3.99 g).

MS (API−): [M−H]⁻ 348.2.

K) 1-amino-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-olhydrochloride

Totert-butyl(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate(2.50 g) was added 4 M hydrogen chloride/ethyl acetate solution (71.6mL). The reaction mixture was stirred at room temperature for 1 hr, andthe solvent was evaporated under reduced pressure. To the residue wasadded diisopropyl ether, and the resulting crystals were collected byfiltration to give the title compound (2.01 g).

MS (API+), found: 250.1.

L)7-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of 4-nitrophenyl7-cyclopropyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate(84 mg) in N,N-dimethylformamide (5 mL) were added1-amino-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-ol hydrochloride(88 mg) and triethylamine (0.099 mL) at room temperature. The reactionmixture was stirred at room temperature for 20 hr, water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed successively with water and saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate), and recrystallized fromhexane/ethyl acetate to give the title compound (52 mg).

MS (API+): [M+H]⁺ 465.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.61-0.71 (2H, m), 0.94-1.05 (5H, m), 1.17(3H, s), 1.91-2.04 (1H, m), 4.25-4.46 (2H, m), 4.68 (1H, d, J=8.3 Hz),4.76 (1H, s), 6.94 (1H, d, J=2.3 Hz), 7.22-7.31 (2H, m), 7.38-7.48 (2H,m), 7.87 (1H, d, J=2.3 Hz), 10.50 (1H, d, J=8.3 Hz), 10.67 (1H, brs).

Example 72-II7-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate

To a solution of 2-chloro-5-iodo-3-nitropyridine (12.0 g) in ethanol(200 mL) were added methyl glycinate hydrochloride (10.6 g) andtriethylamine (11.8 mL) at room temperature. The reaction mixture washeated at reflux for 20 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue wascrystallized from hexane/ethyl acetate to give the title compound (11.1g).

MS (API+): [M+H]⁺ 338.0.

B) 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate (6.00 g)in tetrahydrofuran (300 mL) was added 5% platinum-carbon (500 mg). Thereaction mixture was stirred overnight at room temperature underhydrogen atmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure. The residue was dissolved inethanol (200 mL), the reaction mixture was heated at reflux for 16 hr,and the solvent was evaporated under reduced pressure. The residue waswashed with diisopropyl ether to give the title compound (4.48 g).

MS (API+): [M+H]⁺ 276.0.

C)7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a suspension of 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(3.82 g) in N,N-dimethylformamide (160 mL) was slowly added 1 Mpotassium hexamethyldisilazide/tetrahydrofuran solution (17.4 mL) at 0°C. The reaction mixture was stirred at 0° C. for 1 hr,2-(chloromethoxy)ethyltrimethylsilane (3.62 mL) was slowly addedthereto, and the mixture was stirred at room temperature for 20 hr. Tothe reaction mixture was added water, the insoluble substance wasfiltered off using Celite, and the filtrate was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (NH, hexane/ethyl acetate) to give the titlecompound (2.71 g).

MS (API+): [M+H]⁺ 406.0.

D) methyl2-((tert-butoxycarbonyl)amino)-2-(4-(trifluoromethoxy)phenyl)acetate

To a mixture of 4-trifluoromethoxybenzaldehyde (19.0 g) and ammoniumcarbonate (25.9 g) in a mixed solvent of ethanol (114 mL) and water(45.6 mL) was slowly added an aqueous solution (71.1 mL) of potassiumcyanide (8.14 g) at 50° C. The reaction mixture was stirred at 60° C.for 3 hr, and cooled to room temperature, and the ethanol was evaporatedunder reduced pressure. The pH of the residue was adjusted to 1 withconc. hydrochloric acid at 0° C., and the resulting solid was filteredoff, and washed with water. To an aqueous solution (100 mL) of potassiumhydroxide (23.6 g) was added the solid obtained by the above-mentionedoperation at room temperature, the reaction mixture was stirred at 90°C. for 3 days. The reaction mixture was cooled to room temperature, andneutralized with conc. hydrochloric acid. The resulting solid wascollected by filtration, and washed with water to give a crude product(13.3 g) of 2-amino-2-(4-(trifluoromethoxy)phenyl)acetic acid. To asolution of the obtained crude product (13.3 g) in tetrahydrofuran (113mL) were added di-tert-butyl dicarbonate (19.7 mL) and 2 M aqueoussodium hydroxide solution (85 mL) at room temperature. The reactionmixture was stirred overnight at room temperature, and poured intowater, and the mixture was washed with diethyl ether. The pH of theaqueous layer was adjusted to 3 with 1 M hydrochloric acid at 0° C., andthe mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous magnesium sulfate, andthe solvent was evaporated under reduced pressure to give a crudeproduct (11.3 g) of2-((tert-butoxycarbonyl)amino)-2-(4-(trifluoromethoxy)phenyl)aceticacid. To a solution of the obtained crude product (11.3 g) inN,N-dimethylformamide (84 mL) were added methyl iodide (2.53 mL) andpotassium carbonate (5.59 g) at room temperature. The reaction mixturewas stirred at room temperature for 2 hr, and poured into water, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (8.20 g).

MS (API−): [M−H]⁻ 348.1.

E) tert-butyl(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate

To a solution of methyl2-((tert-butoxycarbonyl)amino)-2-(4-(trifluoromethoxy)phenyl)acetate(5.00 g) in tetrahydrofuran (71.6 mL) was slowly added 1 Mmethylmagnesium bromide/tetrahydrofuran solution (57.3 mL) at 0° C. Thereaction mixture was stirred at 0° C. for 1 hr under argon atmosphere,saturated aqueous ammonium chloride solution was added thereto at 0° C.,and the mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous magnesium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (3.99 g).

MS (API−): [M−H]⁻ 348.2.

F) 1-amino-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-olhydrochloride

Totert-butyl(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate(2.50 g) was added 4 M hydrogen chloride/ethyl acetate solution (71.6mL). The reaction mixture was stirred at room temperature for 1 hr, andthe solvent was evaporated under reduced pressure. To the residue wasadded diisopropyl ether, and the resulting crystals were collected byfiltration to give the title compound (2.01 g).

MS (API+), found: 250.1.

G)N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-iodo-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(3.40 g) in tetrahydrofuran (120 mL) was slowly added a solution ofbis(trichloromethyl)carbonate (1.99 g) in tetrahydrofuran (20 mL) atroom temperature under nitrogen atmosphere. The reaction mixture wasstirred at 40° C. for 5 hr under nitrogen atmosphere, and the solventwas evaporated under reduced pressure. To the residue was addedtetrahydrofuran, and the solvent was evaporated under reduced pressure.The operation (addition of tetrahydrofuran and then evaporation) wasrepeated three times. The residue was diluted with tetrahydrofuran (120mL), and slowly added to a mixture of1-amino-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-ol hydrochloride(2.64 g) and triethylamine (3.51 mL) in tetrahydrofuran (20 mL) at roomtemperature. The reaction mixture was stirred overnight at 60° C., waterwas added thereto, and the mixture was extracted with ethyl acetate. Theextract was washed with saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel chromatography (NH,hexane/ethyl acetate) to give the title compound (5.32 g).

MS (API+): [M+H]⁺ 681.1.

H)7-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

A mixture ofN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-iodo-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(5.32 g), cyclopropylboronic acid (1.34 g), palladium(II) acetate (0.176g), tricyclohexylphosphine (0.438 g) and tripotassium phosphate (4.98 g)in a mixed solvent of toluene (150 mL) and water (6.01 mL) was stirredunder argon atmosphere at 80° C. for 3 hr, at 100° C. for 3 hr, at roomtemperature for 3 days, and at 100° C. for 2.5 hr, water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed successively with water and saturated brine, the aqueouslayers were combined, and extracted with ethyl acetate. The extract wasdried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (3.80g).

MS (API+): [M+H]⁺ 595.3.

I)7-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To7-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(3.80 g) were slowly added trifluoroacetic acid (120 mL) and water (14mL). The reaction mixture was stirred at room temperature for 1 hr, andthe solvent was evaporated under reduced pressure. The residue wasdissolved in N,N-dimethylformamide (220 mL), and 7 M ammonia/methanolsolution (18.3 mL) was slowly added thereto. The reaction mixture wasstirred at room temperature for 2 hr, ethyl acetate was added thereto,and the mixture was washed successively with water and saturated brine.The aqueous layer was neutralized with 1 M hydrochloric acid, andextracted with ethyl acetate. The extract was dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was dissolved in ethyl acetate, and the solutionwas washed successively with water and saturated brine, and dried overanhydrous magnesium sulfate. The solvent was evaporated under reducedpressure to give the title compound (2.65 g).

MS (API+): [M+H]⁺ 465.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.60-0.71 (2H, m), 0.94-1.04 (5H, m), 1.18(3H, s), 1.90-2.05 (1H, m), 4.25-4.47 (2H, m), 4.68 (1H, d, J=8.3 Hz),4.78 (1H, s), 6.94 (1H, d, J=2.3 Hz), 7.23-7.33 (2H, m), 7.38-7.48 (2H,m), 7.88 (1H, d, J=2.3 Hz), 10.51 (1H, d, J=7.9 Hz), 10.68 (1H, brs).

Example 737-cyclopropyl-N-((1S)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(2.65 g) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=850/150), and recrystallized from hexane/ethyl acetate togive the title compound having a shorter retention time (1.01 g).

MS (API+): [M+H]⁺ 465.1.

¹H NMR (300 MHz, DMSO-d₆) δ 0.62-0.71 (2H, m), 0.95-1.05 (5H, m), 1.17(3H, s), 1.91-2.04 (1H, m), 4.25-4.47 (2H, m), 4.68 (1H, d, J=7.9 Hz),4.77 (1H, s), 6.94 (1H, d, J=1.9 Hz), 7.22-7.32 (2H, m), 7.38-7.47 (2H,m), 7.87 (1H, d, J=2.3 Hz), 10.50 (1H, d, J=8.3 Hz), 10.67 (1H, s).

Example 747-cyclopropyl-N-((1R)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(2.65 g) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=850/150), and recrystallized from hexane/ethyl acetate togive the title compound having a longer retention time (0.792 g).

MS (API+): [M+H]⁺ 465.1.

¹H NMR (300 MHz, DMSO-d₆) δ 0.62-0.71 (2H, m), 0.94-1.05 (5H, m), 1.17(3H, s), 1.91-2.05 (1H, m), 4.25-4.46 (2H, m), 4.68 (1H, d, J=8.3 Hz),4.77 (1H, s), 6.94 (1H, d, J=1.9 Hz), 7.23-7.32 (2H, m), 7.38-7.47 (2H,m), 7.87 (1H, d, J=2.3 Hz), 10.50 (1H, d, J=8.3 Hz), 10.67 (1H, s).

Example 75-I7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate

To a solution of 2-chloro-5-iodo-3-nitropyridine (12.0 g) in ethanol(200 mL) were added methyl glycinate hydrochloride (10.6 g) andtriethylamine (11.8 mL) at room temperature. The reaction mixture washeated at reflux for 20 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue wascrystallized from hexane/ethyl acetate to give the title compound (11.1g).

MS (API+): [M+H]⁺ 338.0.

B) 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate (6.00 g)in tetrahydrofuran (300 mL) was added 5% platinum-carbon (500 mg). Thereaction mixture was stirred overnight at room temperature underhydrogen atmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure. The residue was dissolved inethanol (200 mL), the solution was heated at reflux for 16 hr, and thesolvent was evaporated under reduced pressure. The residue was washedwith diisopropyl ether to give the title compound (4.48 g).

MS (API+): [M+H]⁺ 276.0.

C)7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a suspension of 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(3.82 g) in N,N-dimethylformamide (160 mL) was slowly added 1 Mpotassium hexamethyldisilazide/tetrahydrofuran solution (17.4 mL) at 0°C. The reaction mixture was stirred at 0° C. for 1 hr,2-(chloromethoxy)ethyltrimethylsilane (3.62 mL) was slowly addedthereto, and the mixture was stirred at room temperature for 20 hr. Tothe reaction mixture was added water, the insoluble substance wasfiltered off using Celite, and the filtrate was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (NH, hexane/ethyl acetate) to give the titlecompound (2.71 g).

MS (API+): [M+H]⁺ 406.0.

D) 3-fluoro-N-methoxy-N-methyl-4-(trifluoromethoxy)benzamide

To a solution of 3-fluoro-4-(trifluoromethoxy)benzoic acid (20 g),N,O-dimethylhydroxylamine hydrochloride (10.5 g) and triethylamine (24.9mL) in N,N-dimethylformamide (300 mL) were added 1-hydroxybenzotriazolemonohydrate (16.4 g) and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimidehydrochloride (20.5 g) at room temperature. The reaction mixture wasstirred overnight at room temperature, and then at 50° C. for 1.5 hr. Tothe reaction mixture was added saturated aqueous sodium hydrogencarbonate solution, and the mixture was extracted with ethyl acetate.The extract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. Toluene was added to the residue because theresidue contained a small amount of N,N-dimethylformamide, and thesolvent was evaporated under reduced pressure to give the title compound(22.0 g).

MS (API+): [M+H]⁺ 268.1.

E) 3-fluoro-4-(trifluoromethoxy)benzaldehyde

To a solution of3-fluoro-N-methoxy-N-methyl-4-(trifluoromethoxy)benzamide (10.0 g) intetrahydrofuran (101 mL) was added 1.5 M diisobutylaluminiumhydride/toluene solution (27.4 mL) at 0° C. The reaction mixture wasstirred overnight at room temperature, saturated aqueous ammoniumchloride solution and 6 M hydrochloric acid was successively added, andthe mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous magnesium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (3.55 g).

¹H NMR (300 MHz, DMSO-d₆) δ 7.71-7.97 (2H, m), 7.97-8.10 (1H, m), 10.02(1H, d, J=1.9 Hz).

F) 2-amino-2-(3-fluoro-4-(trifluoromethoxy)phenyl)acetic acid

To a mixture of 3-fluoro-4-(trifluoromethoxy)benzaldehyde (3.50 g) andammonium carbonate (4.36 g) in a mixed solvent of ethanol (21 mL) andwater (8 mL) was slowly added an aqueous solution (13 mL) of potassiumcyanide (1.37 g) at 50° C. The mixture was stirred at 60° C. for 4 hr,and cooled to room temperature, and the ethanol was evaporated underreduced pressure. The pH of the residue was adjusted to 1 with conc.hydrochloric acid at 0° C., and the mixture was left overnight atfreezer. The resulting solid was collected by filtration, and washedwith water. To an aqueous solution (100 mL) of potassium hydroxide (3.96g) was added the obtained solid at room temperature, and the mixture wasstirred at 90° C. for 60 hr, cooled to room temperature, and neutralizedwith conc. hydrochloric acid. The resulting solid was collected byfiltration, and washed with water to give the title compound (937 mg).

¹H NMR (300 MHz, DMSO-d₆) δ 4.34 (1H, s), 7.22-7.42 (1H, m), 7.45-7.66(2H, m).

G)2-((tert-butoxycarbonyl)amino)-2-(3-fluoro-4-(trifluoromethoxy)phenyl)aceticacid

To a solution of 2-amino-2-(3-fluoro-4-(trifluoromethoxy)phenyl)aceticacid (937 mg) in tetrahydrofuran (7.40 mL) were added di-tert-butyldicarbonate (1.29 mL) and 2 M aqueous sodium hydroxide solution (5.55mL) at room temperature. The reaction mixture was stirred at roomtemperature for 3 days, and poured into water, and the mixture waswashed with diethyl ether. The pH of the aqueous layer was adjusted to 3with 1 M hydrochloric acid at 0° C., and the mixture was extracted withethyl acetate. The extract was washed with saturated brine, and driedover anhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure to give the title compound (750 mg).

¹H NMR (300 MHz, DMSO-d₆) δ 1.39 (9H, s), 5.02-5.35 (1H, m), 7.15-7.64(3H, m), 7.64-7.85 (1H, m).

H) methyl2-((tert-butoxycarbonyl)amino)-2-(3-fluoro-4-(trifluoromethoxy)phenyl)acetate

To a solution of2-((tert-butoxycarbonyl)amino)-2-(3-fluoro-4-(trifluoromethoxy)phenyl)aceticacid (750 mg) in N,N-dimethylformamide (5.5 mL) were added methyl iodide(0.159 mL) and potassium carbonate (352 mg) at room temperature. Thereaction mixture was stirred at room temperature for 4 hr under nitrogenatmosphere, and poured into water, and the mixture was extracted withethyl acetate. The extract was washed with saturated brine, and driedover anhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (630mg).

MS (API−): [M−H]⁻ 366.1.

I)tert-butyl(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)carbamate

To a solution of methyl2-((tert-butoxycarbonyl)amino)-2-(3-fluoro-4-(trifluoromethoxy)phenyl)acetate(630 mg) in tetrahydrofuran (9 mL) was slowly added 1 M methylmagnesiumbromide/tetrahydrofuran solution (6.86 mL) at 0° C. under argonatmosphere. The reaction mixture was stirred at 0° C. for 4 hr underargon atmosphere, saturated aqueous ammonium chloride solution was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed with saturated brine, and dried over anhydrous magnesiumsulfate, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (hexane/ethylacetate) to give the title compound (540 mg).

MS (API−): [M−H]⁻ 366.2.

J) 1-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methylpropan-2-olhydrochloride

Totert-butyl(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)carbamate(540 mg) was added 4 M hydrogen chloride/ethyl acetate solution (4 mL).The reaction mixture was stirred at room temperature for 30 min, and thesolvent was evaporated under reduced pressure to give the title compound(510 mg).

MS (API+), found: 268.1.

K)N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-iodo-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(586 mg) in tetrahydrofuran (28 mL) was addedbis(trichloromethyl)carbonate (343 mg) at room temperature. The reactionmixture was stirred at 40° C. for 5 hr under nitrogen atmosphere, andthe solvent was evaporated under reduced pressure. To the residue wasadded tetrahydrofuran, and the solvent was evaporated under reducedpressure. The operation (addition of tetrahydrofuran and thenevaporation) was repeated three times. The residue was diluted withtetrahydrofuran (14 mL), and the mixture was slowly added to a solutionof 1-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methylpropan-2-olhydrochloride (439 mg) and triethylamine (0.604 mL) in tetrahydrofuran(9 mL) at room temperature. The reaction mixture was stirred at 60° C.for 16 hr, ethyl acetate was added thereto, washed successively withwater and saturated brine. The organic layer was dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate) to give the title compound (590 mg).

MS (API+): [M+H]⁺ 699.1.

L)7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a mixture ofN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-iodo-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(590 mg), cyclopropylboronic acid (145 mg) and tripotassium phosphate(628 mg) in a mixed solvent of toluene (16.2 mL) and water (0.648 mL)were added palladium(II) acetate (37.9 mg) and tricyclohexylphosphine(95 mg) at room temperature. The reaction mixture was stirred overnightat 100° C. under argon atmosphere, the insoluble substance was filteredoff, and the filtrate was extracted with ethyl acetate. The extract waswashed successively with water and saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (160mg).

MS (API+): [M+H]⁺ 613.2.

M)7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(160 mg) were slowly added trifluoroacetic acid (4 mL) and water (0.4mL) at room temperature. The reaction mixture was stirred at roomtemperature for 1 hr, and the solvent was evaporated under reducedpressure. The residue was dissolved in N,N-dimethylformamide (3 mL), and8 M ammonia/methanol solution (0.5 mL) was slowly added thereto. Thereaction mixture was stirred at room temperature for 30 min, and thesolvent was evaporated under reduced pressure. The residue was dilutedwith ethyl acetate, and the mixture was washed successively with waterand saturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (NH, hexane/ethyl acetate) to givethe title compound (27.0 mg) and the title compound (100 mg) containingan impurity.

MS (API+): [M+H]⁺ 483.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.62-0.70 (2H, m), 0.94-1.04 (5H, m), 1.19(3H, s), 1.91-2.04 (1H, m), 4.25-4.47 (2H, m), 4.68 (1H, d, J=8.3 Hz),4.85 (1H, s), 6.94 (1H, d, J=1.9 Hz), 7.22-7.30 (1H, m), 7.35-7.43 (1H,m), 7.43-7.53 (1H, m), 7.87 (1H, d, J=1.9 Hz), 10.49 (1H, d, J=7.9 Hz),10.67 (1H, brs).

Example 75-II7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a mixture of 4-nitrophenyl7-cyclopropyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate(1.06 g) and1-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methylpropan-2-olhydrochloride (1.09 g) in N,N-dimethylformamide (30 mL) was addedtriethylamine (1.25 mL) at room temperature. The reaction mixture wasstirred at room temperature for 16 hr, water was added thereto, and themixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was crystallized from hexane/ethyl acetate to givethe title compound (1.12 g).

MS (API+): [M+H]⁺ 483.2.

¹H NMR (300 MHz, CDCl₃) δ 0.67-0.76 (2H, m), 0.99-1.09 (2H, m), 1.16(3H, s), 1.37 (3H, s), 1.62 (1H, s), 1.83-1.96 (1H, m), 4.52-4.72 (2H,m), 4.85 (1H, d, J=8.3 Hz), 6.83 (1H, d, J=1.9 Hz), 7.13-7.34 (3H, m),7.88 (1H, d, J=1.9 Hz), 8.57 (1H, s), 10.81 (1H, d, J=8.3 Hz).

Example 76-I Optically active7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

7-Cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(100 mg) containing an impurity, which was obtained in Step M of Example75, was purified by HPLC (C18, mobile phase: water (10 mM, containingNH₄HCO₃)/acetonitrile), and the obtained fraction was concentrated underreduced pressure. Then, the residue was optically resolved by HPLC(column: CHIRALPAK AD, 50 mmID×500 mmL, manufactured by Daicel ChemicalIndustries, Ltd., mobile phase: hexane/ethanol=850/150) to give thetitle compound having a shorter retention time (24 mg).

MS (API+): [M+H]⁺ 483.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.62-0.70 (2H, m), 0.94-1.04 (5H, m), 1.19(3H, s), 1.91-2.03 (1H, m), 4.25-4.46 (2H, m), 4.68 (1H, d, J=8.3 Hz),4.86 (1H, s), 6.94 (1H, d, J=1.9 Hz), 7.22-7.30 (1H, m), 7.35-7.42 (1H,m), 7.43-7.54 (1H, m), 7.87 (1H, d, J=1.9 Hz), 10.49 (1H, d, J=7.9 Hz),10.68 (1H, brs).

Example 76-II Optically active7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

7-Cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(1.25 g) was optically resolved by HPLC (column: CHIRALPAK AD, 50mmID×500 mmL, manufactured by Daicel Chemical Industries, Ltd., mobilephase: hexane/ethanol=850/150), and recrystallized from acetone/heptaneto give the title compound having a shorter retention time (474 mg).

MS (API+): [M+H]⁺ 483.2.

¹H NMR (300 MHz, CDCl₃) δ 0.67-0.76 (2H, m), 0.99-1.09 (2H, m), 1.16(3H, s), 1.37 (3H, s), 1.64 (1H, s), 1.84-1.95 (1H, m), 4.52-4.73 (2H,m), 4.86 (1H, d, J=8.3 Hz), 6.84 (1H, d, J=1.9 Hz), 7.13-7.32 (6H, m),7.88 (1H, d, J=1.9 Hz), 8.81 (1H, brs), 10.82 (1H, d, J=8.3 Hz).

Example 77 Optically active7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

7-Cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(100 mg) containing an impurity, which was obtained in Step M of Example75, was purified by HPLC (C18, mobile phase: water/acetonitrile(containing 0.1% TFA)), and optically resolved by HPLC (column:CHIRALPAK AD, 50 mmID×500 mmL, manufactured by Daicel ChemicalIndustries, Ltd., mobile phase: hexane/ethanol=850/150) to give thetitle compound having a longer retention time (29 mg).

MS (API+): [M+H]⁺ 483.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.62-0.70 (2H, m), 0.95-1.04 (5H, m), 1.19(3H, s), 1.92-2.03 (1H, m), 4.26-4.46 (2H, m), 4.68 (1H, d, J=8.3 Hz),4.86 (1H, s), 6.94 (1H, d, J=2.3 Hz), 7.22-7.29 (1H, m), 7.35-7.42 (1H,m), 7.43-7.53 (1H, m), 7.87 (1H, d, J=2.3 Hz), 10.49 (1H, d, J=8.3 Hz),10.68 (1H, s).

Example 782-oxo-N-(1-(4-(2,2,2-trifluoroethoxyl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) tert-butyl(1-(4-(2,2,2-trifluoroethoxyl)phenyl)propyl)carbamate

To a mixture of tert-butyl(1-(4-hydroxyphenyl)propyl)carbamate (302 mg)and 2,2,2-trifluoroethyl trifluoromethanesulfonate (418 mg) inN,N-dimethylformamide (10 mL) was added potassium carbonate (498 mg).The reaction mixture was stirred at 80° C. for 16 hr, and the solventwas evaporated under reduced pressure. To the residue was added ethylacetate. The organic layer was washed with water, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure to give the title compound (362 mg).

MS (API−): [M−H]⁻332.1.

B)2-oxo-N-(1-(4-(2,2,2-trifluoroethoxyl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

1-(4-(2,2,2-Trifluoroethoxyl)phenyl)propylamine hydrochloride wasobtained fromtert-butyl(1-(4-(2,2,2-trifluoroethoxyl)phenyl)propyl)carbamate in thesame manner as in Step E of Example 18. The title compound was obtainedin the same manner as in Step B of Example 53.

MS (API+): [M+H]⁺409.1.

Example 79N-(2-(methylsulfinyl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained fromN-(2-(methylsulfanyl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidein the same manner as in Example 60.

MS (API+): [M+H]⁺ 443.1.

Example 802-oxo-N-(1-(1-(2,2,2-trifluoroethyl)-1H-imidazol-4-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-trityl-1H-imidazol-4-carbaldehyde

A mixture of 1H-imidazol-4-carbaldehyde (3.00 g), triethylamine (7.00 g)and N,N-dimethylformamide (40 mL) was cooled to 0° C., trityl chloride(10.5 g) was added thereto. The reaction mixture was stirred at roomtemperature for 18 hr, water was added thereto, and the solid wascollected by filtration. The obtained solid was washed with water anddiethyl ether to give the title compound (10.0 g).

¹H NMR (400 MHz, DMSO-d₆) δ 7.11-7.14 (6H, m), 7.40-7.48 (9H, m), 7.67(1H, d, J=0.8 Hz), 7.80 (1H, d, J=1.2 Hz), 9.23 (1H, s).

B) 1-(1-trityl-1H-imidazol-4-yl)propan-1-ol

To a mixture of 1-trityl-1H-imidazol-4-carbaldehyde (1.00 g) andtetrahydrofuran (100 mL) was slowly added 2.96 M ethylmagnesiumbromide/tetrahydrofuran solution (1.50 mL) at 0° C. The reaction mixturewas stirred at room temperature for 18 hr, saturated aqueous ammoniumchloride solution was added thereto, and the mixture was extracted withethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure to give the title compound(1.00 g).

¹H NMR (400 MHz, DMSO-d₆) δ 0.78 (3H, t, J=7.6 Hz), 1.54-1.59 (1H, m),1.68-1.72 (1H, m), 4.36 (1H, t, J=6.0 Hz), 4.81 (1H, d, J=5.6 Hz), 6.65(1H, s), 7.02-7.12 (6H, m), 7.26 (1H, d, J=1.2 Hz), 7.35-7.43 (9H, m).

C) 1-(1-trityl-1H-imidazol-4-yl)propan-1-one

A mixture of 1-(1-trityl-1H-imidazol-4-yl)propan-1-ol (1.00 g),manganese dioxide (2.36 g) and dioxane (20 mL) was heated at reflex for2 hr. The reaction mixture was cooled to room temperature, the insolublesubstance was filtered off, and the filtrate was concentrated underreduced pressure to give the title compound (1.00 g).

¹H NMR (400 MHz, DMSO-d₆) δ 1.03 (3H, t, J=7.6 Hz), 2.86 (2H, q, J=7.6Hz), 7.10-7.15 (6H, m), 7.35-7.80 (10H, m), 7.54 (1H, d, J=1.2 Hz).

D)2-oxo-N-(1-(1-(2,2,2-trifluoroethyl)-1H-imidazol-4-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

A mixture of 1-(1-trityl-1H-imidazol-4-yl)propan-1-one (1.00 g) and 4 Mhydrogen chloride/ethyl acetate solution (40 mL) was stirred at roomtemperature for 2 hr, and the solvent was evaporated under reducedpressure. To the residue was added N,N-dimethylformamide (10 mL),potassium carbonate (829 mg) and 2,2,2-trifluoroethyltrifluoromethanesulfonate (950 mg) was added thereto. The reactionmixture was stirred overnight at room temperature, water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed successively with water and saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(petroleum ether/ethyl acetate) to give1-(1-(2,2,2-trifluoroethyl)-1H-imidazol-4-yl)propan-1-one containing animpurity. To the obtained residue were added hydroxylamine hydrochloride(202 mg), triethylamine (294 mg) and ethanol (20 mL), and the reactionmixture was heated at reflex for 4 hr. The reaction mixture was cooledto room temperature, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. To the residue were addedmethanol (50 mL) and Raney nickel (1.00 g), and the reaction mixture wasstirred at 50° C. for 4 hr under hydrogen atmosphere (50 psi) Thereaction mixture was cooled to room temperature, the insoluble substancewas filtered off, and the filtrate was concentrated under reducedpressure. To the residue were added 4-nitrophenyl2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (491 mg),triethylamine (303 mg) and N,N-dimethylformamide (20 mL), and thereaction mixture was stirred overnight. The reaction mixture waspurified by HPLC (C18, mobile phase: water/acetonitrile (containing 0.1%TFA)), and the obtained solid was crystallized from ethyl acetate togive the title compound (76 mg).

MS (API+): [M+H]⁺383.1.

Example 812-oxo-N-(1-(1-(2,2,2-trifluoroethyl)-1H-1,2,4-triazol-3-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl 1-trityl-1H-1,2,4-triazol-3-carboxylate

The title compound was obtained from methyl1H-1,2,4-triazol-3-carboxylate in the same manner as in Step A ofExample 80.

¹H NMR (400 MHz, DMSO-d₆) δ 3.84 (3H, s), 7.02-7.12 (6H, m), 7.30-7.42(9H, m), 8.39 (1H, s).

B) 1-(1-(2,2,2-trifluoroethyl)-1H-1,2,4-triazol-3-yl)propan-1-one

A mixture of 3.0 M ethylmagnesium bromide/tetrahydrofuran solution (13.2mL) and triethylamine (11.0 g) was stirred at room temperature for 30min. The reaction mixture was cooled to −20° C., a solution of methyl1-trityl-1H-1,2,4-triazol-3-carboxylate (7.30 g) in tetrahydrofuran (150mL) was added thereto, and the mixture was stirred at −20° C. for 1 hr.To the reaction mixture was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (petroleum ether/ethyl acetate) togive the title compound (4.8 g).

¹H NMR (400 MHz, DMSO-d₆) δ 1.04 (3H, t, J=7.6 Hz), 2.97 (2H, q, J=7.6Hz), 7.02-7.10 (6H, m), 7.35-7.43 (9H, m), 8.36 (1H, s).

C)2-oxo-N-(1-(1-(2,2,2-trifluoroethyl)-1H-1,2,4-triazol-3-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(1-(2,2,2-trifluoroethyl)-1H-1,2,4-triazol-3-yl)propan-1-one in thesame manner as in Step D of Example 80.

MS (API+): [M+H]⁺384.1.

Example 82N-(1-(4-isopropoxyphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) tert-butyl(1-(4-isopropoxyphenyl)propyl)carbamate

To a mixture of tert-butyl(1-(4-hydroxyphenyl)propyl)carbamate (628 mg)and 2-iodopropane (0.324 mL) in N,N-dimethylformamide (15 mL) was addedpotassium carbonate (518 mg). The reaction mixture was stirred at roomtemperature for 16 hr, water was added thereto, and the mixture wasextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (309 mg).

¹H NMR (300 MHz, CDCl₃) δ 0.87 (3H, t, J=7.3 Hz), 1.32 (6H, d, J=6.0Hz), 1.41 (9H, s), 1.66-1.83 (2H, m), 4.35-4.61 (2H, m), 4.73 (1H, brs),6.80-6.87 (2H, m), 7.11-7.19 (2H, m)

B)N-(1-(4-isopropoxyphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To tert-butyl(1-(4-isopropoxyphenyl)propyl)carbamate (305 mg) was added4 M hydrogen chloride/ethyl acetate solution (5 mL), and the mixture wasstirred at room temperature for 1 hr. The solvent was evaporated underreduced pressure to give 1-(4-isopropoxyphenyl)propan-1-aminehydrochloride. To a mixture of 4-nitrophenyl2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (297 mg) and1-(4-isopropoxyphenyl)propan-1-amine hydrochloride inN,N-dimethylformamide (10 mL) was added triethylamine (0.395 mL), andthe mixture was stirred at room temperature for 16 hr. To the reactionmixture was added water, and the mixture was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (hexane/ethyl acetate), and crystallized fromhexane/ethyl acetate to give the title compound (178 mg).

MS (API−): [M−H]⁻367.2.

Example 83N-(1-(4-chlorophenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(4-chlorophenyl)propan-1-amine

To a solution of 1-(4-chlorophenyl)propan-1-one (1.69 g) in ethanol (60mL) were added hydroxylamine hydrochloride (1.39 g) and triethylamine(2.79 mL) at room temperature. The reaction mixture was stirred at roomtemperature for 16 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure to give1-(4-chlorophenyl)-N-hydroxypropan-1-imine. To a solution of1-(4-chlorophenyl)-N-hydroxypropan-1-imine in tetrahydrofuran (100 mL)was added 1.1 M borane-tetrahydrofuran complex/tetrahydrofuran solution(27.3 mL), and the mixture was stirred at 80° C. for 16 hr. To thereaction mixture was added 1 M hydrochloric acid, and the mixture wasextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (NH, hexane/ethyl acetate)to give the title compound (520 mg).

¹H NMR (300 MHz, CDCl₃) δ 0.85 (3H, t, J=7.3 Hz), 1.58-1.74 (2H, m),3.80 (1H, t, J=7.0 Hz), 7.21-7.40 (4H, m).

B)N-(1-(4-chlorophenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a mixture of 4-nitrophenyl2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (300 mg) and1-(4-chlorophenyl)propan-1-amine (211 mg) in N,N-dimethylformamide (10mL) was added triethylamine (0.279 mL), and the mixture was stirred atroom temperature for 16 hr. To the reaction mixture was added water, andthe mixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate), and recrystallized from hexane/ethyl acetate togive the title compound (205 mg).

MS (API+): [M+H]⁺345.1.

Example 842-oxo-N-(1-(2-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) N-methoxy-N-methyl-2-(trifluoromethoxy)benzamide

To a mixture of 2-(trifluoromethoxy)benzoic acid (5.00 g),N,O-dimethylhydroxylamine hydrochloride (2.63 g), and triethylamine(7.36 g) in N,N-dimethylformamide (50 mL) were added1-hydroxybenzotriazole monohydrate (4.94 g) and1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (2.63 g).The reaction mixture was stirred at 10° C. for 16 hr, water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed with saturated brine, and dried over anhydrous sodiumsulfate, and the solvent was evaporated under reduced pressure to givethe title compound (5.21 g).

¹H NMR (400 MHz, CDCl₃) δ 3.36 (3H, s), 3.45 (3H, s), 7.27-7.37 (2H, m),7.39-7.50 (2H, m).

B) N-hydroxy-1-(2-(trifluoromethoxy)phenyl)propan-1-imine

The title compound was obtained fromN-methoxy-N-methyl-2-(trifluoromethoxy)benzamide in the same manner asin Steps C-D of Example 2.

¹H NMR (400 MHz, CDCl₃) δ 1.05 (3H, t, J=7.6 Hz), 2.77 (2H, q, J=7.6Hz), 7.27-7.35 (2H, m), 7.36-7.44 (2H, m), 8.28 (1H, s).

C) 1-(2-(trifluoromethoxy)phenyl)propan-1-amine hydrochloride

To a solution of N-hydroxy-1-(2-(trifluoromethoxy)phenyl)propan-1-imine(2.31 g) in methanol (100 mL) was added Raney nickel (1.00 g). Thereaction mixture was stirred at 50° C. for 4 hr under hydrogenatmosphere (50 psi), the insoluble substance was filtered off, and thefiltrate was concentrated under reduced pressure. The residue wasdissolved in a mixed solvent of ethyl acetate (70 mL) and methanol (10mL), 4 M hydrogen chloride/ethyl acetate solution (40 mL) was addedthereto. The reaction mixture was stirred at 15° C. for 2 hr, and thesolvent was evaporated under reduced pressure. The obtained solid waswashed with tert-butyl methyl ether to give the title compound (1.36 g).

MS (API+): [M+H]⁺219.9.

D)2-oxo-N-(1-(2-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(2-(trifluoromethoxy)phenyl)propan-1-amine hydrochloride in the samemanner as in Step L of Example 72-I.

MS (API+): [M+H]⁺395.1.

Example 85N-(1-(4-methylphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl 4-(difluoromethyl)benzoate

To a solution of methyl 4-formylbenzoate (821 mg) in toluene (25 mL) wasadded N,N-diethylaminosulfur trifluoride (1.98 mL). The reaction mixturewas stirred at room temperature for 20 hr, water was added thereto, andthe mixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate), and crystallized from hexane/ethyl acetate togive the title compound (619 mg).

¹H NMR (300 MHz, CDCl₃) δ 3.95 (3H, s), 6.46-6.92 (1H, m), 7.59 (2H, d,J=8.3 Hz), 8.13 (2H, d, J=8.7 Hz).

B) 4-(difluoromethyl)-N-methoxy-N-methylbenzamide

To a solution of methyl 4-(difluoromethyl)benzoate (615 mg) in a mixedsolvent of tetrahydrofuran (15 mL) and methanol (5 mL) was added 2 Maqueous sodium hydroxide solution (3.0 mL), and the mixture was stirredat room temperature for 3 hr. The reaction mixture was neutralized with1 M hydrochloric acid, and the mixture was extracted with ethyl acetate.The extract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. A mixture of the obtained residue,N,O-dimethylhydroxylamine hydrochloride (387 mg), triethylamine (0.921mL), l-hydroxybenzotriazole monohydrate (607 mg) and1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (760 mg) inN,N-dimethylformamide (15 mL) was stirred at room temperature for 20 hr.To the reaction mixture was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (540 mg).

¹H NMR (300 MHz, CDCl₃) δ 3.38 (3H, s), 3.54 (3H, s), 6.47-6.89 (1H, m),7.56 (2H, d, J=8.3 Hz), 7.77 (2H, d, J=8.7 Hz).

C) 1-(4-(difluoromethyl)phenyl)propan-1-one

The title compound was obtained from4-(difluoromethyl)-N-methoxy-N-methylbenzamide in the same manner as inStep C of Example 2.

¹H NMR (300 MHz, CDCl₃) δ 1.24 (3H, t, J=7.2 Hz), 3.03 (2H, q, J=7.2Hz), 6.48-6.90 (1H, m), 7.61 (2H, d, J=8.3 Hz), 8.05 (2H, d, J=8.7 Hz).

D) 1-(4-methylphenyl)propan-1-amine

To a solution of 1-(4-(difluoromethyl)phenyl)propan-1-one (360 mg) inethanol (10 mL) were added hydroxylamine hydrochloride (272 mg) andtriethylamine (0.545 mL). The reaction mixture was stirred at roomtemperature for 16 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. To the residue were addedethanol (20 mL) and 20% palladium hydroxide-carbon (40 mg). The reactionmixture was stirred at room temperature for 16 hr under hydrogenatmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure to give the title compound (280 mg).

¹H NMR (300 MHz, CDCl₃) δ 0.72 (3H, t, J=7.2 Hz), 1.66-1.94 (2H, m),2.31 (3H, s), 3.73 (1H, dd, J=8.7, 5.7 Hz), 7.08-7.23 (4H, m), 8.26 (2H,brs).

E)N-(1-(4-methylphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 1-(4-methylphenyl)propan-1-amine inthe same manner as in Step B of Example 83.

MS (API+): [M+H]⁺325.2.

Example 862-oxo-N-(1-(1-(2,2,2-trifluoroethyl)-1H-pyrazol-4-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl 1H-pyrazol-4-carboxylate

A mixture of 1H-pyrazol-4-carboxylic acid (4.00 g) and 4 M hydrogenchloride/methanol solution (150 mL) was stirred overnight at roomtemperature, and the solvent was evaporated under reduced pressure togive the title compound (5.0 g).

¹H NMR (400 MHz, DMSO-d₆) δ 3.72 (3H, s), 8.09 (2H, s), 11.62 (1H, s).

B) methyl 1-trityl-1H-pyrazol-4-carboxylate

The title compound was obtained from methyl 1H-pyrazole-4-carboxylate inthe same manner as in Step A of Example 80.

¹H NMR (400 MHz, DMSO-d₆) δ 3.79 (3H, s), 7.11-7.14 (6H, m), 7.31-7.33(9H, s) 7.93 (1H, s), 8.04 (1H, s).

C) N-methoxy-N-methyl-1-trityl-1H-pyrazole-4-carboxamide

A mixture of methyl 1-trityl-1H-pyrazol-4-carboxylate (8.00 g) andlithium hydroxide (2.70 g) in water/tetrahydrofuran/methanol (1:2:2)(100 mL) was stirred at 60° C. for 3 hr, and the solvent was evaporatedunder reduced pressure. To the residue were added N,N-dimethylformamide(50 mL), N,O-dimethylhydroxylamine hydrochloride (2.10 g), triethylamine(6.80 g) and O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluroniumhexafluorophosphorate (16.8 g) at room temperature. The reaction mixturewas stirred overnight at room temperature, water was added thereto, andthe mixture was extracted with ethyl acetate. The extract was washedsuccessively with aqueous sodium carbonate solution, water and saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure to give the title compound (5.7 g).

¹H NMR (400 MHz, DMSO-d₆) δ 3.29 (3H, s), 3.63 (3H, s), 7.13-7.16 (6H,m), 7.31-7.33 (9H, s) 7.98 (1H, s), 8.11 (1H, s).

D)2-oxo-N-(1-(1-(2,2,2-trifluoroethyl)-1H-pyrazol-4-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained fromN-methoxy-N-methyl-1-trityl-1H-pyrazol-4-carboxamide in the same manneras in Step C of Example 2 and Step D of Example 80.

MS (API+): [M+H]⁺383.1.

Example 87N-(1-(3-methyl-4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-bromo-3-methyl-4-(trifluoromethoxy)benzene in the same manner as inSteps A-B of Example 30, Step D of Example 2, Step C of Example 56 andStep G of Example 7.

MS (API+): [M+H]⁺409.1.

Example 88N-(2-(dimethylamino)-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)tert-butyl(2-amino-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate

A mixture of 2-amino-2-(4-(trifluoromethoxy)phenyl)acetamide (2.15 g),di-tert-butyldicarbonate (2.41 g) and tetrahydrofuran (50 mL) wasstirred overnight at room temperature. The solvent was evaporated underreduced pressure to give the title compound (2.99 g).

¹H NMR (300 MHz, CDCl₃) δ 1.41 (9H, s), 5.24 (1H, brs), 5.67 (1H, brs),5.83 (1H, d, J=5.7 Hz), 5.91 (1H, brs), 7.16-7.24 (2H, m), 7.37-7.49(2H, m).

B)tert-butyl(2-(dimethylamino)-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate

A mixture of 2 M aqueous sodium hydroxide solution (20 mL),tert-butyl(2-amino-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate(1.5 g) and methanol (15 mL) was stirred at 70° C. for 2 days. Thereaction mixture was neutralized with 1 M hydrochloric acid at 0° C.,and the mixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reduced pressureto give a pale yellow solid (1.26 g). A mixture of the obtained solid(400 mg), triethylamine (0.166 mL), 1-hydroxybenzotriazole monohydrate(219 mg), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride(274 mg), dimethylamine hydrochloride (117 mg) and N,N-dimethylformamide(5 mL) was stirred overnight at 80° C. The reaction mixture was pouredinto saturated aqueous sodium hydrogen carbonate solution, and themixture was extracted with ethyl acetate. The extract was washedsuccessively with saturated aqueous sodium hydrogen carbonate solutionand saturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (254 mg).

¹H NMR (300 MHz, CDCl₃) δ 1.41 (9H, s), 2.90 (3H, s), 2.99 (3H, s), 5.56(1H, d, J=7.5 Hz), 6.08 (1H, d, J=7.5 Hz), 7.14-7.23 (2H, m), 7.36-7.46(2H, m).

C)N-(2-(dimethylamino)-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

A mixture oftert-butyl(2-(dimethylamino)-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate(270 mg) and 2 M hydrogen chloride/methanol solution (5 mL) was stirredat room temperature for 30 min, and the solvent was evaporated underreduced pressure. To the residue were added N,N-dimethylformamide (15mL), triethylamine (226 mg) and4-nitrophenyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate(234 mg), and the mixture was stirred overnight at room temperature. Tothe reaction mixture was added saturated brine, and the mixture wasextracted with ethyl acetate. The extract was washed with 1 M aqueoussodium hydroxide solution and saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate) and then silica gel column chromatography (ethylacetate/methanol) to give the title compound (83 mg).

MS (API+): [M+H]⁺438.1.

Example 89N-(2-(methylamino)-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Steps A-C ofExample 88.

MS (API+): [M+H]⁺424.1.

Example 90N-(2-isopropoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-isopropoxy-1-(4-(trifluoromethoxy)phenyl)ethanamine

The title compound was obtained in the same manner as in Step D ofExample 63, Step C of Example 1 and Step B of Example 54.

MS (API+): [M+H]⁺264.1.

B)N-(2-isopropoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-isopropoxy-1-(4-(trifluoromethoxy)phenyl)ethanamine in the same manneras in Step B of Example 83.

MS (API+): [M+H]⁺439.2.

Example 91N-(2-(cyclopentyloxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-(cyclopentyloxy)-1-(4-(trifluoromethoxy)phenyl)ethanamine

The title compound was obtained in the same manner as in Step D ofExample 63, Step C of Example 1 and Step B of Example 54.

MS (API+): [M+H]⁺290.2.

B)N-(2-(cyclopentyloxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-(cyclopentyloxy)-1-(4-(trifluoromethoxy)phenyl)ethanamine in the samemanner as in Step B of Example 83.

MS (API+): [M+H]⁺465.2.

Example 92N-(3-amino-3-oxo-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)tert-butyl(3-amino-3-oxo-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate

To a solution of3-((tert-butoxycarbonyl)amino)-3-(4-(trifluoromethoxy)phenyl)propanoicacid (700 mg) in N,N-dimethylformamide (25.0 mL) were added1H-benzotriazol-1-ol ammonium salt (335 mg) and1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (431 mg).The reaction mixture was stirred overnight at room temperature, waterwas added thereto, and the precipitated solid was collected byfiltration, and washed with water to give the title compound (740 mg).

MS (API−): [M−H]⁻347.2.

B) 3-amino-3-(4-(trifluoromethoxy)phenyl)propanamide hydrochloride

Totert-butyl(3-amino-3-oxo-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate(740 mg) was added 4 M hydrogen chloride/ethyl acetate solution (10 mL).The reaction mixture was stirred at room temperature for 1 hr, and theprecipitated solid was collected by filtration, and washed with ethylacetate to give the title compound (413 mg).

MS (API+), found: 249.1.

C)N-(3-amino-3-oxo-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from3-amino-3-(4-(trifluoromethoxy)phenyl)propanamide hydrochloride in thesame manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺424.1.

Example 93N-(3-(dimethylamino)-3-oxo-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)tert-butyl(3-(dimethylamino)-3-oxo-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate

To a solution of3-((tert-butoxycarbonyl)amino)-3-(4-(trifluoromethoxy)phenyl)propanoicacid (600 mg) in N,N-dimethylformamide (25 mL) were added1-hydroxybenzotriazole monohydrate (353 mg),1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (437 mg),N-methylmethanamine (1.12 mL) and triethylamine (725 μL). The reactionmixture was stirred overnight at room temperature, water was addedthereto, and the precipitated solid was collected by filtration, andwashed with water to give the title compound (600 mg).

MS (API−): [M−H]⁻375.1.

B) 3-amino-N,N-dimethyl-3-(4-(trifluoromethoxy)phenyl)propanamidehydrochloride

The title compound was obtained fromtert-butyl(3-(dimethylamino)-3-oxo-1-(4-(trifluoromethoxy)phenyl)propyl)carbamatein the same manner as in Step B of Example 92.

MS (API+), found: 277.1.

C)N-(3-(dimethylamino)-3-oxo-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from3-amino-N,N-dimethyl-3-(4-(trifluoromethoxy)phenyl)propanamidehydrochloride in the same manner as in Step H of Example 72-I.

MS (API+): [M+H]⁺452.2.

Example 94N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethylamine hydrochloride in thesame manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺425.2.

Example 953-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl 2-((3-nitropyridin-2-yl)amino)propanoate

The title compound was obtained from methyl 2-aminopropanoatehydrochloride in the same manner as in Step A of Example 19.

MS (API+): [M+H]⁺225.8.

B) 3-methyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl 2-((3-nitropyridin-2-yl)amino)propanoate (18.0g) in ethanol (500 mL) were added iron powder (17.9 g) and conc.hydrochloric acid (2 mL). The reaction mixture was heated at reflex for16 hr, the insoluble substance was filtered off, and the filtrate wasconcentrated under reduced pressure. The residue was purified by HPLC(C18, mobile phase: water/acetonitrile (containing 0.1% TFA)), and theobtained fraction was concentrated under reduced pressure. To theresidue was added conc. hydrochloric acid (1 mL), and the mixture wasconcentrated under reduced pressure. To the residue was added saturatedaqueous sodium hydrogen carbonate solution, the reaction mixture wasstirred at 15° C. for 16 hr, and the solid was collected by filtration.The obtained solid was washed with water, and dried under reducedpressure to give the title compound (1.2 g).

MS (API+): [M+H]⁺163.8.

C)3-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from3-methyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one in the same manner asin Step F of Example 1.

MS (API+): [M+H]⁺409.1.

Example 96N-(1-(4-(difluoromethyl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(4-(difluoromethyl)phenyl)propan-1-one in the same manner as in StepsA-B of Example 83.

MS (API+): [M+H]⁺361.2.

Example 97N-(2-cyano-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)tert-butyl(3-amino-3-oxo-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate

The title compound was obtained in the same manner as in Step A ofExample 92.

MS (API−): [M−H]⁻347.1.

B) tert-butyl(2-cyano-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate

To a solution oftert-butyl(3-amino-3-oxo-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate(425 mg) in tetrahydrofuran (30.0 mL) was added thionyl chloride (281μL). The reaction mixture was stirred overnight at 60° C., and thesolvent was evaporated under reduced pressure. To the residue was addedwater, and the mixture was extracted with ethyl acetate. The extract waswashed with saturated aqueous sodium hydrogen carbonate solution andsaturated brine, dried over anhydrous sodium sulfate, and the solventwas evaporated under reduced pressure. The residue was purified bysilica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (251 mg).

MS (API−): [M−H]⁻329.1.

C) 3-amino-3-(4-(trifluoromethoxy)phenyl)propanenitrile hydrochloride

The title compound was obtained fromtert-butyl(2-cyano-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate in thesame manner as in Step B of Example 92.

¹H NMR (300 MHz, DMSO-d₆) δ 3.23-3.44 (2H, m), 4.80 (1H, dd, J=8.3, 6.0Hz), 7.52 (2H, d, J=7.9 Hz), 7.72-7.84 (2H, m), 9.01 (3H, brs).

D)N-(2-cyano-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from3-amino-3-(4-(trifluoromethoxy)phenyl)propanenitrile hydrochloride inthe same manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺406.2.

Example 982-oxo-N-(1-(3-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(3-(trifluoromethoxy)phenyl)propan-1-amine hydrochloride

The title compound was obtained from 3-(trifluoromethoxy)benzoic acid inthe same manner as in Step A of Example 84, Steps C-D of Example 2 andStep C of Example 84.

¹H NMR (400 MHz, DMSO-d₆) δ 0.75 (3H, t, J=7.2 Hz), 1.71-1.85 (1H, m),1.92-2.05 (1H, m), 4.17-4.28 (1H, m), 7.34-7.42 (1H, m), 7.51-7.61 (3H,m), 8.66 (3H, brs).

B)2-oxo-N-(1-(3-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(3-(trifluoromethoxy)phenyl)propan-1-amine hydrochloride in the samemanner as in Step L of Example 72-I.

MS (API+): [M+H]⁺395.2.

Example 99N-(1-(4-cyclopropylphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(4-cyclopropylphenyl)propan-1-one

A mixture of 1-(4-bromophenyl)propan-1-one (1.07 g), cyclopropylboronicacid (0.558 g),(1,1-bis(diphenylphosphino)ferrocene)dichloropalladium(II) (183 mg),tripotassium phosphate (2.12 g) in a mixed solvent of1,2-dimethoxyethane (15 mL) and water (5 mL) was stirred at 85° C. for20 hr under nitrogen atmosphere. To the reaction mixture was addedwater, and the mixture was extracted with ethyl acetate. The extract waswashed with saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (679 mg).

MS (API+): [M+H]⁺174.9.

B)N-(1-(4-cyclopropylphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 1-(4-cyclopropylphenyl)propan-1-onein the same manner as in Steps A-B of Example 83.

MS (API+): [M+H]⁺351.2.

Example 100N-(3-methoxy-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(4-(trifluoromethoxy)phenyl)prop-2-en-1-ol

To a solution of 4-(trifluoromethoxy)benzaldehyde (12.0 g) intetrahydrofuran (200 mL) was slowly added 1 M vinylmagnesiumbromide/tetrahydrofuran solution (69.5 mL) under nitrogen atmosphere, at−78° C. The reaction mixture was allowed to be slowly warmed to roomtemperature, and stirred at room temperature for 16 hr under nitrogenatmosphere. To the reaction mixture was added saturated aqueous ammoniumchloride solution, and the mixture was extracted with ethyl acetate. Theextract was washed with saturated brine, and dried over anhydrous sodiumsulfate, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (petroleumether/ethyl acetate) to give the title compound (11.8 g).

¹H NMR (400 MHz, DMSO-d₆) δ 5.02-5.13 (2H, m), 5.26 (1H, dt, J=17.2, 1.6Hz), 5.64 (1H, d, J=4.4 Hz), 5.87-5.99 (1H, m), 7.31 (2H, d, J=8.0 Hz),7.44 (2H, dd, J=6.8, 1.6 Hz).

B) 1-(4-(trifluoromethoxy)phenyl)prop-2-en-1-one

To a solution of 1-(4-(trifluoromethoxy)phenyl)prop-2-en-1-ol (9.80 g)in dichloromethane (150 mL) was added manganese(IV) dioxide (39.1 g).The reaction mixture was stirred at room temperature for 2 days, theinsoluble substance was filtered off, and the filtrate was concentratedunder reduced pressure. The residue was purified by silica gel columnchromatography (petroleum ether/ethyl acetate) to give the titlecompound (2.75 g).

¹H NMR (400 MHz, CDCl₃) δ 5.97 (1H, dd, J=10.8, 1.6 Hz), 6.46 (1H, dd,J=17.2, 1.6 Hz), 7.13 (1H, dd, J=17.2, 10.8 Hz), 7.31 (2H, dd, J=8.8,0.8 Hz), 8.00 (2H, dd, J=6.8, 2.0 Hz).

C) 3-methoxy-1-(4-(trifluoromethoxy)phenyl)propan-1-one

A mixture of 1-(4-(trifluoromethoxy)phenyl) prop-2-en-1-one (2.75 g),methanol (407 mg) and bis(acetonitrile)dichloropalladium(II) (328 mg) indichloromethane (30 mL) was stirred at room temperature for 16 hr undernitrogen atmosphere, dichloromethane was added thereto, and theinsoluble substance was filtered off. The filtrate was concentratedunder reduced pressure, and the residue was purified by silica gelcolumn chromatography (petroleum ether/ethyl acetate) to give the titlecompound (2.80 g).

¹H NMR (400 MHz, CDCl₃) δ 3.22 (2H, t, J=6.4 Hz), 3.38 (3H, s), 3.82(2H, t, J=6.4 Hz), 7.29 (2H, d, J=8.4 Hz), 8.02 (2H, dd, J=6.8, 2.0 Hz).

D) 3-methoxy-1-(4-(trifluoromethoxy)phenyl)propan-1-amine hydrochloride

The title compound was obtained from3-methoxy-1-(4-(trifluoromethoxy)phenyl)propan-1-one in the same manneras in Steps D-F of Example 2.

MS (API+): [M+H]⁺250.0.

E)N-(3-methoxy-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from3-methoxy-1-(4-(trifluoromethoxy)phenyl)propan-1-amine hydrochloride inthe same manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺425.2.

Example 1012-oxo-N-(2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl) ethanamine

To a mixture of 4-(trifluoromethoxy)phenacyl bromide (3.00 g) andtriethylamine (1.61 g) in tetrahydrofuran (15 mL) was added pyrrolidine(0.902 g). The reaction mixture was stirred at room temperature for 1hr, water was added thereto, and the mixture was extracted withdichloromethane. The extract was dried over anhydrous sodium sulfate,and the solvent was evaporated under reduced pressure to give2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethanone (3.20 g). Toa solution of 2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethanone(3.20 g) in ethanol (30 mL) were added hydroxylamine hydrochloride(0.805 g) and triethylamine (1.18 g). The reaction mixture was stirredat 78° C. for 16 hr, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(petroleum ether/ethyl acetate) to giveN-hydroxy-2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethanimine(1.12 g). To a solution ofN-hydroxy-2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethanimine(1.12 g) in methanol (50 mL) was added Raney nickel (300 mg) at roomtemperature. The reaction mixture was stirred at 50° C. for 3 hr underhydrogen atmosphere (50 psi), the insoluble substance was filtered off,and the filtrate was concentrated under reduced pressure to give thetitle compound (1.01 g).

MS (API+): [M+H]⁺274.9.

B)tert-butyl(2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate

To a mixture of2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethanamine (1.01 g)and triethylamine (558 mg) in methanol (15 mL) was added di-tert-butyldicarbonate (1.20 g) at room temperature. The reaction mixture wasstirred at room temperature for 4 hr, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (petroleum ether/ethyl acetate) and then HPLC (C18,mobile phase: water/acetonitrile (containing 0.1% NH₄HCO₃)) to give thetitle compound (560 mg).

¹H NMR (400 MHz, CDCl₃) δ 1.39 (9H, s), 1.71-1.85 (4H, m), 2.41-2.69(5H, m), 2.73-2.86 (1H, m), 4.51-4.71 (1H, m), 5.58-5.78 (1H, m), 7.16(2H, d, J=8.0 Hz), 7.32 (2H, d, J=8.4 Hz).

C) 2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethanaminehydrochloride

Totert-butyl(2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate(560 mg) was added 4 M hydrogen chloride/ethyl acetate solution (20 mL)at room temperature. The reaction mixture was stirred at roomtemperature for 2 hr, and the solvent was evaporated under reducedpressure to give the title compound (310 mg).

¹H NMR (400 MHz, CD₃OD) δ 2.02-2.15 (4H, m), 3.35-3.58 (4H, m), 3.97(2H, d, J=6.8 Hz), 5.00 (1H, t, J=6.8 Hz), 7.49 (2H, d, J=8.0 Hz), 7.80(2H, d, J=8.8 Hz).

D)2-oxo-N-(2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethanaminehydrochloride in the same manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺450.2.

Example 1022-oxo-N-(2-(2-oxopyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 5-methoxy-3,4-dihydro-2H-pyrrole

A mixture of pyrrolidine (7.30 g) and dimethyl sulfate (12.1 g) wasstirred at 60° C. for 18 hr, water was added thereto, and the pH of themixture was adjusted to 8-9 with saturated potassium carbonate aqueoussolution. The reaction mixture was extracted with tert-butyl methylether, dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure to give the title compound (7.2 g).

¹H NMR (400 MHz, CDCl₃) δ 1.89-1.99 (2H, m), 2.30-2.40 (2H, m),3.52-3.60 (2H, m), 3.71 (3H, s).

B) 1-(2-oxo-2-(4-(trifluoromethoxy)phenyl)ethyl)pyrrolidin-2-one

A mixture of 5-methoxy-3,4-dihydro-2H-pyrrole (5.60 g) and2-bromo-1-(4-(trifluoromethoxy)phenyl)ethanone (3.00 g) inN,N-dimethylformamide (20 mL) was stirred at 50-60° C. for 5 hr, waterwas added thereto, and the mixture was extracted with ethyl acetate. Theextract was washed with saturated brine, and dried over anhydrous sodiumsulfate, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (petroleumether/ethyl acetate) to give the title compound (2.32 g).

¹H NMR (400 MHz, CDCl₃) δ 2.01-2.15 (2H, m), 2.48 (2H, t, J=8.0 Hz),3.50 (2H, t, J=7.2 Hz), 4.70 (2H, s), 7.31 (2H, d, J=8.0 Hz), 8.03 (2H,d, J=8.8 Hz).

C) 1-(2-amino-2-(4-(trifluoromethoxy)phenyl)ethyl)pyrrolidin-2-one

A mixture of1-(2-oxo-2-(4-(trifluoromethoxy)phenyl)ethyl)pyrrolidin-2-one (2.32 g)and hydroxylamine hydrochloride (1.12 g) in pyridine (20 mL) was stirredat 12° C. for 16 hr, water was added thereto, and the mixture wasextracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure to give1-(2-(hydroxyimino)-2-(4-(trifluoromethoxy)phenyl)ethyl)pyrrolidin-2-one(2.19 g). A mixture of1-(2-(hydroxyimino)-2-(4-(trifluoromethoxy)phenyl)ethyl)pyrrolidin-2-one(1.00 g) and 10% palladium-carbon (dry, 100 mg) in methanol (50 mL) wasstirred at 25° C. for 18 hr under hydrogen atmosphere. The insolublesubstance was filtered off through Celite, and the filtrate wasconcentrated under reduced pressure. The residue was purified by silicagel column chromatography (dichloromethane/methanol) to give the titlecompound (700 mg).

MS (API+): [M+H]⁺288.9.

D)2-oxo-N-(2-(2-oxopyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step B ofExample 83.

MS (API+): [M+H]⁺464.2.

Example 1033-(((2-oxo-2,3-dihydropyrido[2,3-b]pyrazin-4(1H)-yl)carbonyl)amino)-3-(4-(trifluoromethoxy)phenyl)propylacetate

The title compound was obtained fromtert-butyl(3-hydroxy-1-(4-(trifluorofluoromethoxy)phenyl)propyl)carbamate in the same manner as in Step E of Example 18 and Step L ofExample 72-I.

MS (API+): [M+H]⁺453.2.

Example 104N-(3-hydroxy-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of3-(((2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-yl)carbonyl)amino)-3-(4-(trifluoromethoxy)phenyl)propylacetate (115 mg) in methanol (5 mL) was added potassium carbonate (45.7mg). The reaction mixture was stirred at room temperature for 1 hr, andthe solvent was evaporated under reduced pressure. To the residue wasadded water, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was recrystallized from hexane/ethylacetate to give the title compound (89.4 mg).

MS (API+): [M+H]⁺410.8.

Example 105N-(1-(4-(azetidin-1-yl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(4-(azetidin-1-yl)phenyl)propan-1-one

A mixture of 1-(4-bromophenyl)propan-1-one (639 mg), azetidine (0.303mL), tris(dibenzylideneacetone)dipalladium(0) (137 mg),4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (174 mg) and sodiumtert-butoxide (432 mg) in toluene (15 mL) was stirred at 85° C. for 20hr under nitrogen atmosphere. To the reaction mixture was added water,and the mixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate) to give the title compound (414 mg).

¹H NMR (300 MHz, CDCl₃) δ 1.20 (3H, t, J=7.3 Hz), 2.42 (2H, quin, J=7.3Hz), 2.90 (2H, q, J=7.2 Hz), 3.99 (4H, t, J=7.3 Hz), 6.32-6.39 (2H, m),7.82-7.90 (2H, m).

B)N-(1-(4-(azetidin-1-yl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(4-(azetidin-1-yl)phenyl)propan-1-one in the same manner as in StepsD-E of Example 2 and Step B of Example 83.

MS (API−): [M−H]⁻364.2.

Example 106N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(1.90 g) was resolved by HPLC (column: CHIRALPAK IC, 46 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=400/600) to give the title compound having a shorterretention time (815 mg).

MS (API+): [M+H]⁺425.2.

Example 107N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(1.90 g) was resolved by HPLC (column: CHIRALPAK IC, 46 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=400/600) to give the title compound having a longerretention time (772 mg).

MS (API+): [M+H]⁺425.1.

Example 108N-(2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)tert-butyl(2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate

To a solution oftert-butyl(2-hydroxy-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate (4.00g) in acetonitrile (120 mL) were added copper(I) iodide (3.57 g) anddifluoro(fluorosulfonyl)acetic acid (1.93 mL) at room temperature. Thereaction mixture was stirred overnight at room temperature, saturatedaqueous ammonium chloride solution was added thereto, and the mixturewas extracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (hexane/ethyl acetate) to give the titlecompound (673 mg).

MS (API−): [M−H]⁻370.1.

B) 2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethanaminehydrochloride

The title compound was obtained fromtert-butyl(2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamatein the same manner as in Step B of Example 92.

MS (API+): [M+H]⁺272.1.

C)N-(2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethanaminehydrochloride in the same manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺447.1.

Example 109N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-bromo-1-(4-(trifluoromethyl)phenyl)ethanone in the same manner as inSteps D-E of Example 63 and Step L of Example 72-I.

MS (API+): [M+H]⁺395.1.

Example 110N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-nitrophenyl7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate and2-methoxy-1-(4-(trifluoromethyl)phenyl)ethan-1-amine in the same manneras in Step L of Example 72-I.

MS (API+): [M+H]⁺409.2.

Example 111N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-nitrophenyl2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate and2-methoxy-1-(3-fluoro-4-(trifluoromethoxy)phenyl)ethan-1-amine in thesame manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺429.1.

Example 112N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-nitrophenyl7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate and2-methoxy-1-(3-fluoro-4-(trifluoromethoxy)phenyl)ethan-1-amine in thesame manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺443.1.

Example 113N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(6-chloro-3-nitropyridin-2-yl)glycinate

The title compound was obtained in the same manner as in Step A ofExample 37.

¹H NMR (300 MHz, DMSO-d₆) δ 3.67 (3H, s), 4.27 (2H, d, J=6.0 Hz), 6.87(1H, d, J=8.7 Hz), 8.48 (1H, d, J=8.7 Hz), 8.96 (1H, t, J=5.7 Hz).

B) methyl N-(3-nitro-6-(1H-pyrazol-1-yl)pyridin-2-yl)glycinate

To a solution of methyl N-(6-chloro-3-nitropyridin-2-yl)glycinate (1.02g) in N,N-dimethylacetamide (10 mL) was added 1H-pyrazole (844 mg) atroom temperature. The reaction mixture was stirred at 120° C. for 16 hr,water was added thereto, and the mixture was extracted with ethylacetate/tetrahydrofuran. The extract was washed successively with waterand saturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (293 mg).

MS (API+): [M+H]⁺278.1.

C) 6-(1H-pyrazol-1-yl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

The title compound was obtained from methyl2-((3-nitro-6-(1H-pyrazol-1-yl)pyridin-2-yl)amino)acetate in the samemanner as in Step C of Example 72-I.

MS (API−): [M−H]⁻214.1.

D) 4-nitrophenyl2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate

The title compound was obtained from6-(1H-pyrazol-1-yl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one in thesame manner as in Step F of Example 7.

MS (API+): [M+H]⁺381.1.

E)N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-nitrophenyl2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylateand 2-methoxy-1-(3-fluoro-4-(trifluoromethoxy)phenyl)ethan-1-amine inthe same manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺495.2.

Example 1147-cyclopropyl-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained fromN-(1-(4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-iodo-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidein the same manner as in Step L of Example 75 and Step I of Example 63.

MS (API+): [M+H]⁺451.2.

Example 1157-cyclopropyl-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-methoxy-1-(4-(trifluoromethyl)phenyl)ethan-1-amine hydrochloride inthe same manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺435.2.

Example 116N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-nitrophenyl2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylateand 2-methoxy-1-(4-(trifluoromethyl)phenyl)ethan-1-amine hydrochloridein the same manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺477.2.

Example 117N-((1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(118 mg) was resolved by SFC (column: CHIRALCEL OJH, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140) to give the title compound having a shorterretention time (31.0 mg).

MS (API+): [M+H]⁺495.2.

Example 118N-((1R)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(118 mg) was resolved by SFC (column: CHIRALCEL OJH, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140) to give the title compound having a longerretention time (41.8 mg).

MS (API+): [M+H]⁺495.1.

Example 1197-cyclopropyl-N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-cyclopropyl-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(245 mg) was resolved by SFC (column: CHIRALCEL OJH, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140) to give the title compound having a shorterretention time (98.6 mg).

MS (API+): [M+H]⁺451.2.

Example 1207-cyclopropyl-N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-cyclopropyl-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(245 mg) was resolved by SFC (column: CHIRALCEL OJH, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140) to give the title compound having a longerretention time (102 mg).

MS (API+): [M+H]⁺451.2.

Example 121N-((1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(184 mg) was resolved by SFC (column: CHIRALPAK IA, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140) to give the title compound having a shorterretention time (70.1 mg).

MS (API+): [M+H]⁺429.1.

Example 122N-((1R)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(184 mg) was resolved by SFC (column: CHIRALPAK IA, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140) to give the title compound having a longerretention time (73.6 mg).

MS (API+): [M+H]⁺429.1.

Example 123N-((1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(203 mg) was resolved by SFC (column: CHIRALPAK IA, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140) to give the title compound having a shorterretention time (61.0 mg).

MS (API+): [M+H]⁺443.1.

Example 124N-((1R)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(203 mg) was resolved by SFC (column: CHIRALPAK IA, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140) to give the title compound having a longerretention time (78.8 mg).

MS (API+): [M+H]⁺443.1.

Example 1257-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-methoxy-1-(3-fluoro-4-(trifluoromethoxy)phenyl)ethan-1-aminehydrochloride in the same manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺469.2.

Example 126 Optically activeN-(2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(243 mg) was resolved by SFC (column: CHIRALPAK IC, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=770/230) to give the title compound having a shorterretention time (81.1 mg).

MS (API+): [M+H]⁺447.1.

Example 127 Optically activeN-(2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(243 mg) was resolved by SFC (column: CHIRALPAK IC, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=770/230) to give the title compound having a longerretention time (81.4 mg).

MS (API+): [M+H]⁺447.1.

Example 1287-cyclopropyl-N-((1R)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(129 mg) was resolved by HPLC (column: CHIRALPAK IC, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=600/400) to give the title compound having a shorterretention time (58.2 mg).

MS (API+): [M+H]⁺469.2.

Example 1297-cyclopropyl-N-((1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(129 mg) was resolved by HPLC (column: CHIRALPAK IC, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=600/400) to give the title compound having a longerretention time (60.7 mg).

MS (API+): [M+H]⁺469.2.

Example 130N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(142 mg) was resolved by SFC (column: CHIRALCEL OJH, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140) to give the title compound having a shorterretention time (53.5 mg).

MS (API+): [M+H]⁺477.2.

Example 131N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(142 mg) was resolved by SFC (column: CHIRALCEL OJH, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=860/140) to give the title compound having a longerretention time (57.3 mg).

MS (API+): [M+H]⁺477.2.

Example 132N-(1-(4-bromophenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(4-bromophenyl)-N-hydroxy-2-methoxyethanimine

The title compound was obtained from 2-bromo-1-(4-bromophenyl)ethanonein the same manner as in Step D of Example 63 and Step D of Example 2.

MS (API+): [M+H]⁺244.1.

B) 1-(4-bromophenyl)-2-methoxyethanamine

A mixture of 1-(4-bromophenyl)-N-hydroxy-2-methoxyethanimine (7.5 g),1.1 M borane-tetrahydrofuran complex/tetrahydrofuran solution (55.9 mL)and tetrahydrofuran (300 mL) was stirred at 80° C. for 2 days, 1 Maqueous sodium hydroxide solution was added thereto, and the mixture wasstirred at 80° C. for 3 hr. To the reaction mixture was added saturatedbrine, and the mixture was extracted with ethyl acetate. The extract waswashed with saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure to give the titlecompound containing an impurity (8.44 g).

MS (API+): [M+H]⁺230.1.

C)N-(1-(4-bromophenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-nitrophenyl7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate and1-(4-bromophenyl)-2-methoxyethanamine in the same manner as in Step G ofExample 7.

MS (API+): [M+H]⁺419.1.

Example 133N-(2-(2-methoxyethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-(trifluoromethoxy)phenacylbromide in the same manner as in Step D of Example 63, Step D of Example2, Step B of Example 15 and Step G of Example 7.

MS (API+): [M+H]⁺469.2.

Example 134N-(2-methoxy-1-(4-(H-pyrazol-1-yl)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(4-bromophenyl)-2-methoxyethanone

The title compound was obtained from 2-bromo-1-(4-bromophenyl)ethanonein the same manner as in Step D of Example 63.

¹H NMR (300 MHz, CDCl₃) δ 3.50 (3H, s), 4.65 (2H, s), 7.55-7.68 (2H, m),7.75-7.87 (2H, m).

B) 2-(4-bromophenyl)-2-(methoxymethyl)-1,3-dioxolane

A mixture of 1-(4-bromophenyl)-2-methoxyethanone (3.00 g),p-toluenesulfonic acid monohydrate (0.249 g), ethylene glycol (1.63 g)and toluene (50 mL) was stirred overnight using Dean-Stark at 140° C.The reaction mixture was filtered through silica gel pad (NH), and thesolvent was evaporated under reduced pressure to give the title compound(3.97 g).

¹H NMR (300 MHz, CDCl₃) δ 3.39 (3H, s), 3.57 (2H, s), 3.76-3.92 (2H, m),4.02-4.19 (2H, m), 7.35-7.43 (2H, m), 7.43-7.52 (2H, m).

C) 1-(4-(2-(methoxymethyl)-1,3-dioxolane-2-yl)phenyl)-1H-pyrazole

A mixture of 2-(4-bromophenyl)-2-(methoxymethyl)-1,3-dioxolane (3.5 g),1H-pyrazole (0.960 g), quinolin-8-ol (0.372 g), copper(I) iodide (0.244g), potassium carbonate (3.54 g) and dimethyl sulfoxide (50 mL) wasstirred overnight at 140° C. under nitrogen atmosphere, water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed successively with saturated aqueous ammonium chloridesolution and saturated brine, dried over anhydrous magnesium sulfate,and filtered through NH silica gel pad. The filtrate was concentratedunder reduced pressure, and the residue was purified by silica gelcolumn chromatography (hexane/ethyl acetate) to give the title compound(2.53 g).

MS (API+): [M+H]⁺261.1.

D) 2-methoxy-1-(4-(1H-pyrazol-1-yl)phenyl)ethanone

A mixture of1-(4-(2-(methoxymethyl)-1,3-dioxolane-2-yl)phenyl)-1H-pyrazole (2.6 g),1 M hydrochloric acid (15 mL) and tetrahydrofuran (30 mL) was stirredovernight at room temperature, saturated brine was added thereto, andthe mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous magnesium sulfate, andthe solvent was evaporated under reduced pressure to give the titlecompound (2.15 g).

¹H NMR (300 MHz, CDCl₃) δ 3.52 (3H, s), 4.71 (2H, s), 6.48-6.56 (1H, m),7.78 (1H, d, J=1.9 Hz), 7.79-7.87 (2H, m), 8.02 (1H, d, J=2.6 Hz),8.03-8.10 (2H, m).

E)N-(2-methoxy-1-(4-(1H-pyrazol-1-yl)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-methoxy-1-(4-(1H-pyrazol-1-yl)phenyl)ethanone in the same manner as inStep D of Example 2, Step B of Example 15 and Step G of Example 7.

MS (API+): [M+H]⁺407.2.

Example 135N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-(1-methyl-1H-pyrazol-3-yl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(5-bromo-3-nitropyridin-2-yl)glycinate

The title compound was obtained from 5-bromo-2-chloro-3-nitropyridine inthe same manner as in Step A of Example 19.

MS (API+): [M+H]⁺290.0.

B) 7-bromo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

A mixture of methyl N-(5-bromo-3-nitropyridin-2-yl)glycinate (18.0 g)and 5% platinum-carbon (1.80 g) in tetrahydrofuran (414 mL) was stirredat room temperature for 1 hr under hydrogen atmosphere. The catalyst wasfiltered off, and the solvent was evaporated under reduced pressure. Theresidue was dissolved in ethanol (200 mL), the solution was stirredovernight at 80° C. The reaction mixture was cooled to room temperature,and the solid was collected by filtration, and washed with ethyl acetateto give the title compound (9.60 g).

¹H NMR (300 MHz, DMSO-d₆) δ 3.94 (2H, d, J=1.7 Hz), 6.99 (1H, s), 7.01(1H, d, J=2.1 Hz), 7.65 (1H, d, J=2.3 Hz), 10.46 (1H, s).

C)7-bromo-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]-pyrazine-4(1H)-carboxamide

The title compound was obtained from7-bromo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one in the same manner asin Steps C-D of Example 26.

MS (API+): [M+H]⁺619.2.

D)N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-(1-methyl-1H-pyrazol-3-yl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]-pyrazine-4(1H)-carboxamide

To a mixture of7-bromo-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]-pyrazine-4(1H)-carboxamide(100 mg) and1-methyl-3-(4,4,5,5-tetramethyl-[1,3,2]-dioxaborolane-1H-pyrazole (101mg), tripotassium phosphate (103 mg) in a mixed solvent of toluene (1.51mL) and water (0.10 mL) was addedbis(di-tert-butyl(4-dimethylaminophenyl)phosphine)dichloropalladium(II)(11.4 mg) at room temperature, the reaction mixture was stirred at 100°C. for 3 hr under argon atmosphere. The reaction mixture was cooled toroom temperature, and the solvent was evaporated under reduced pressure.The residue was purified by silica gel column chromatography(hexane/ethyl acetate) to give the title compound (72 mg).

MS (API+): [M+H]⁺621.3.

E)N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-(1-methyl-1H-pyrazol-3-yl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained fromN-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-(1-methyl-H-pyrazol-3-yl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]-pyrazine-4(1H)-carboxamidein the same manner as in Step I of Example 63.

MS (API+): [M+H]⁺491.2.

Example 136N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-(1-methyl-1H-pyrazol-4-yl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from7-bromo-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]-pyrazine-4(1H)-carboxamide(100 mg) and1-methyl-4-(4,4,5,5-tetramethyl-[1,3,2]-dioxaborolane-1H-pyrazole in thesame manner as in Step D of Example 135 and Step I of Example 63.

MS (API+): [M+H]⁺491.2.

Example 137N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-(1-methyl-1H-pyrazol-5-yl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from7-bromo-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]-pyrazine-4(1H)-carboxamide(100 mg) and1-methyl-5-(4,4,5,5-tetramethyl-[1,3,2]-dioxaborolane-1H-pyrazole in thesame manner as in Step D of Example 135 and Step I of Example 63.

MS (API+): [M+H]⁺491.2.

Example 1387-isopropoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 2-iodopropane in the same manner asin Steps H-I of Example 63.

MS (API+): [M+H]⁺469.1.

Example 1397-(difluoromethoxy)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)7-(difluoromethoxy)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a mixture of7-hydroxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(163 mg) and N-benzyl-N,N,N-triethylammonium chloride (20.4 mg) intetrahydrofuran (2.00 mL) was added 8 M aqueous sodium hydroxidesolution (36.3 μL) at 0° C. The reaction mixture was stirred overnightat room temperature under chloro(difluoro)methane atmosphere. To thereaction mixture was added water, and the mixture was extracted withethyl acetate. The extract was washed with saturated brine, and driedover anhydrous sodium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (80.9mg).

MS (API+): [M+H]⁺607.2.

B)7-(difluoromethoxy)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from7-(difluoromethoxy)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidein the same manner as in Step I of Example 63.

MS (API+): [M+H]⁺477.2.

Example 140N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-oxo-6,7-dihydropteridine-8(5H)-carboxamideA) methyl 2-((2-chloro-5-nitropyrimidin-4-yl)aminoacetate

The title compound was obtained from 2,4-dichloro-5-nitropyrimidine inthe same manner as in Step A of Example 1.

MS (API−): [M−H]⁻245.0.

B) 7,8-dihydropteridin-6(5H)-one

To a solution of methyl 2-((2-chloro-5-nitropyrimidin-4-yl)aminoacetate(7.23 g) in ethanol (293 mL) was added 5% palladium-carbon (containing50% water, 3.00 g) at room temperature. The reaction mixture was stirredat room temperature for 2 hr under hydrogen atmosphere, the catalyst wasfiltered off, and the solvent was evaporated under reduced pressure. Toa solution of the residue in ethanol (293 mL) was added acetic acid(8.39 mL) at room temperature. The reaction mixture was stirred at 80°C. for 3 days, and cooled to room temperature, and the solid wascollected by filtration. The obtained solid was suspended in saturatedaqueous sodium bicarbonate solution, and the solid was collected byfiltration, and washed with water to give the title compound (3.91 g).

¹H NMR (300 MHz, DMSO-d₆) δ 4.02 (2H, d, J=1.5 Hz), 7.66 (1H, s), 7.70(1H, brs), 8.05 (1H, s), 10.49 (1H, brs).

D)N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-oxo-6,7-dihydropteridin-8(5H)-carboxamide

The title compound was obtained from 7,8-dihydropteridin-6(5H)-one inthe same manner as in Steps F-G of Example 7.

MS (API+): [M+H]⁺412.2.

Example 1417-ethoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from iodoethane in the same manner as inSteps H-I of Example 63.

MS (API+): [M+H]⁺455.2.

Example 1427-methyl-N-(oxetan-3-yl(4-(trifluoromethoxy)phenyl)methyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) diethyl(4-(trifluoromethoxy)benzyl)malonate

A mixture of 1-(bromomethyl)-4-(trifluoromethoxy)benzene (10.0 g),diethyl malonate (6.91 g), sodium ethoxide (14.7 g) and ethanol (500 mL)was stirred at 80° C. for 2 days. To the reaction mixture was addedsaturated aqueous ammonium chloride solution, and the mixture wasextracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (hexane/ethyl acetate) to give the titlecompound (7.46 g).

MS (API−): [M−H]⁻333.1.

B) 2-(4-(trifluoromethoxy)benzyl)propane-1,3-diol

To a mixture of diethyl(4-(trifluoromethoxy)benzyl)malonate (5.3 g) andtetrahydrofuran (100 mL) was added lithium aluminium hydride (2.41 g) at0° C. The reaction mixture was stirred at 0° C. for 30 min, 1 Mhydrochloric acid was added thereto, and the mixture was extracted withethyl acetate. The extract was washed with saturated brine, and driedover anhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure to give a residue (4.32 g). The same reaction wasrepeated. The obtained residue (total 5.3 g) was purified by silica gelcolumn chromatography (hexane/ethyl acetate) to give the title compound(2.9 g).

¹H NMR (300 MHz, CDCl₃) δ 1.89-2.12 (1H, m), 2.34 (2H, brs), 2.65 (2H,d, J=7.5 Hz), 3.60-3.72 (2H, m), 3.75-3.87 (2H, m), 7.08-7.17 (2H, m),7.17-7.24 (2H, m).

C) 3-(4-(trifluoromethoxy)benzyl)oxetane

To a mixture of 2-(4-(trifluoromethoxy)benzyl)propane-1,3-diol (2.37 g)and tetrahydrofuran (100 mL) was added 1.6 M n-butyllithium/hexanesolution (6.51 mL) at 0° C. The reaction mixture was stirred at 0° C.for 30 min under nitrogen atmosphere, p-toluenesulfonyl chloride (1.99g) was added thereto at room temperature, and the mixture was stirred atroom temperature for 1 hr under nitrogen atmosphere. To the reactionmixture was added 1.6 M n-butyllithium/hexane solution (7.10 mL) at roomtemperature, and the mixture was stirred at 80° C. for 4 hr undernitrogen atmosphere. To the reaction mixture was added saturated aqueousammonium chloride solution, and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (0.950g).

¹H NMR (300 MHz, CDCl₃) δ 3.03 (2H, d, J=7.9 Hz), 3.15-3.43 (1H, m),4.46 (2H, t, J=6.0 Hz), 4.80 (2H, dd, J=7.5, 6.0 Hz), 7.13 (4H, s).

D) 3-(bromo(4-(trifluoromethoxy)phenyl)methyl)oxetane

A mixture of 3-(4-(trifluoromethoxy)benzyl)oxetane (950 mg),N-bromosuccinimide (947 mg), 2,2′-azobis(2-methylpropionitrile) (67.2mg) and benzotrifluoride (20 mL) was stirred overnight at 80° C. To thereaction mixture was added hexane, the insoluble substance was filteredoff, and the filtrate was concentrated under reduced pressure. Theresidue was purified by silica gel column chromatography (hexane/ethylacetate) to give the title compound (406 mg).

¹H NMR (300 MHz, CDCl₃) δ 3.68-3.87 (1H, m), 4.17 (1H, t, J=6.4 Hz),4.54-4.66 (2H, m), 4.92 (1H, dd, J=7.4, 6.6 Hz), 5.32 (1H, d, J=11.1Hz), 7.14-7.24 (2H, m), 7.35-7.43 (2H, m).

E) 3-(azido(4-(trifluoromethoxy)phenyl)methyl)oxetane

A mixture of 3-(bromo(4-(trifluoromethoxy)phenyl)methyl)oxetane (230mg), sodium azide (80 mg), water (3 mL) and acetone (12 mL) was stirredovernight at room temperature, saturated aqueous sodium hydrogencarbonate solution was added thereto, and the mixture was extracted withethyl acetate. The extract was washed with saturated brine, and driedover anhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure to give the title compound (260 mg).

¹H NMR (300 MHz, CDCl₃) δ 3.18-3.41 (1H, m), 4.33 (1H, t, J=6.2 Hz),4.54-4.71 (2H, m), 4.80-4.89 (2H, m), 7.21-7.27 (2H, m), 7.29-7.36 (2H,m).

F)7-methyl-N-(oxetan-3-yl(4-(trifluoromethoxy)phenyl)methyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

A mixture of 3-(azido(4-(trifluoromethoxy)phenyl)methyl)oxetane (260mg), 5% palladium-carbon (containing 50% water, 30 mg) andtetrahydrofuran (5 mL) was stirred at room temperature for 1 hr underhydrogen atmosphere. Then, to the reaction mixture was added methanol (5mL), the reaction mixture was stirred overnight at room temperatureunder hydrogen atmosphere. The insoluble substance was filtered offthrough Celite, and the filtrate was concentrated under reduced pressureto give oxetan-3-yl(4-(trifluoromethoxy)phenyl)methanamine (209 mg). Thetitle compound was obtained from the obtainedoxetan-3-yl(4-(trifluoromethoxy)phenyl)methanamine in the same manner asin Step G of Example 7.

MS (API+): [M+H]⁺437.1.

Example 143N-(1-(3-fluoro-4-(1H-pyrazol-1-yl)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-bromo-1-(4-bromo-3-fluorophenyl)ethanone

To a solution of 1-(4-bromo-3-fluorophenyl)ethanone (2.8 g) (obtainedfrom 4-bromo-3-fluorobenzonitrile in the same manner as in Step B ofExample 30) in tetrahydrofuran (150 mL) was addedphenyltrimethylammonium tribromide (4.35 g) at 0° C. The reactionmixture was stirred at room temperature for 2 days, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (hexane/ethyl acetate) to give the titlecompound (3.58 g).

¹H NMR (300 MHz, CDCl₃) δ 4.33-4.42 (2H, m), 7.59-7.77 (3H, m).

B)N-(1-(3-fluoro-4-(1H-pyrazol-1-yl)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-bromo-1-(4-bromo-3-fluorophenyl)ethanone in the same manner as inSteps A-D of Example 134, Step D of Example 2, Step B of Example 15 andStep G of Example 7.

MS (API+): [M+H]⁺425.2.

Example 144N-(2-methoxy-1-(5-(1H-pyrazol-1-yl)pyridin-2-yl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 5-bromopicoline acid in the samemanner as in Step A of Example 31, Steps D-F of Example 66, Steps A-D ofExample 134, Step D of Example 2, Step B of Example 15 and Step G ofExample 7.

MS (API+): [M+H]⁺408.2.

Example 145N-((1R)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(30.1 mg) was resolved by HPLC (column: CHIRALPAK IC, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=800/200) to give the title compound having a shorterretention time (10.0 mg).

MS (API+): [M+H]⁺425.2.

Example 146N-((1S)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(30.1 mg) was resolved by HPLC (column: CHIRALPAK IC, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=800/200) to give the title compound having a longerretention time (9.4 mg).

MS (API+): [M+H]⁺425.2.

Example 1477-methyl-2-oxo-N-(1-(4-(1H-pyrrol-1-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(4-(1H-pyrrol-1-yl)phenyl)propan-1-one

To a mixture of 1H-pyrrole (1.38 g), 1-(4-bromophenyl)propan-1-one (3.66g), trans-N,N′-bismethyl-1,2-cyclohexane (489 mg) and tripotassiumphosphate (7.66 g) in toluene (20 mL) was added copper(I) iodide (164mg). The reaction mixture was heated at reflex for 16 hr under argonatmosphere, ethyl acetate and water were added thereto. The insolublesubstance was filtered off, and the organic layer and aqueous layer ofthe filtrate were separated, and the aqueous layer was extracted withethyl acetate. The extract was dried over anhydrous sodium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (2.32 g).

¹H NMR (300 MHz, DMSO-d₆) δ 1.10 (3H, t, J=7.3 Hz), 3.06 (2H, q, J=7.2Hz), 6.28-6.37 (2H, m), 7.46-7.57 (2H, m), 7.68-7.80 (2H, m), 7.96-8.10(2H, m).

B)7-methyl-2-oxo-N-(1-(4-(1H-pyrrol-1-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(4-(1H-pyrrol-1-yl)phenyl)propan-1-one in the same manner as in Step Cof Example 1, Step B of Example 54 and Step G of Example 7.

MS (API+): [M+H]⁺390.2.

Example 1487-methyl-2-oxo-N-(1-(4-(pyrrolidin-1-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(4-(1H-pyrrol-1-yl)phenyl)propan-1-one in the same manner as in Step Cof Example 1, Step B of Example 54 and Step G of Example 7.

MS (API+): [M+H]⁺394.3.

Example 1497-(2-hydroxypropan-2-yl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl 4-((2-methoxy-1-(4-trifluoromethoxy)phenyl)ethyl)carbamoyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-7-carboxylate

A mixture of7-bromo-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(537 mg) and 1,1′-bis(diphenylphosphino)ferrocene dichloropalladium(II)dichloromethane complex (70.8 mg), triethylamine (0.242 mL) and methanol(1.5 mL) in N,N-dimethylformamide (15 mL) was stirred at 80° C. for 3 hrunder carbon monoxide atmosphere (5 atm). The reaction mixture wascooled, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (hexane/ethylacetate) to give the title compound (403 mg).

MS (API+): [M+H]⁺599.3.

C) methyl 4-((2-methoxy-1-(4-trifluoromethoxy)phenyl)ethyl)carbamoyl)-2-oxo-1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-7-carboxylate

The title compound was obtained from methyl4-((2-methoxy-1-(4-trifluoromethoxy)phenyl)ethyl)carbamoyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-7-carboxylatein the same manner as in Step I of Example 63.

MS (API+): [M+H]⁺469.1.

D)7-(2-hydroxypropan-2-yl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of methyl4-((2-methoxy-1-(4-trifluoromethoxy)phenyl)ethyl)carbamoyl)-2-oxo-1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-7-carboxylate(40 mg) in tetrahydrofuran (0.85 mL) was added 1 M methylmagnesiumbromide/tetrahydrofuran solution (0.43 mL) at 0° C. The reaction mixturewas stirred at 0° C. for 2 hr under argon atmosphere, 1 Mmethylmagnesium bromide/tetrahydrofuran solution (0.85 mL) was addedthereto. The reaction mixture was stirred at 0° C. for 30 min, saturatedaqueous ammonium chloride solution was added thereto at 0° C., and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (27 mg).

MS (API+): [M+H]⁺469.2.

Example 1507-(azetidin-1-yl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)7-(azetidin-1-yl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a mixture of7-bromo-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(300 mg), azetidine (32.6 μL), and cesium carbonate (249 mg) in toluene(4.84 mL) were added(9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine) (28.0 mg) andtris(dibenzylideneacetone)dipalladium(0) (29.6 mg), the reaction mixturewas stirred overnight at 110° C. under nitrogen atmosphere. The reactionmixture was diluted with ethyl acetate, and the mixture was washed withsaturated brine. The organic layer was dried over anhydrous sodiumsulfate, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (hexane/ethylacetate) to give the title compound (19.3 mg).

MS (API+): [M+H]⁺596.3.

B)7-(azetidin-1-yl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from7-(azetidin-1-yl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidein the same manner as in Step I of Example 63.

MS (API+): [M+H]⁺466.2.

Example 151N-(1-(imidazo[1,2-a]pyridin-7-yl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from imidazo[1,2-a]pyridine-7-carboxylicacid in the same manner as in Step A of Example 31, Step B of Example30, Step D of Example 2, Step B of Example 132 and Step G of Example 7.

MS (API+): [M+H]⁺365.2.

Example 1527-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)cyclopropyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(4-(trifluoromethoxy)phenyl)cyclopropaneamine

To a mixture of 4-(trifluoromethoxy)benzonitrile (2.02 g) andtitanium(IV) tetraisopropoxide (3.48 mL) in diethyl ether (50 mL) wasslowly added 3 M ethylmagnesium bromide/tetrahydrofuran solution (7.91mL) over 50 min at −78° C. The reaction mixture was stirred at roomtemperature for 1 hr, boron trifluoride diethyl ether complex (3.01 mL)was added thereto. The reaction mixture was stirred at room temperaturefor 16 hr, 1 M hydrochloric acid and diethyl ether were added thereto.Then, 2 M aqueous sodium hydroxide solution was added thereto, and themixture was extracted with diethyl ether. The extract was dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure to give the title compound (1.51 g).

MS (API+): [M+H]⁺218.1.

B)7-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)cyclopropyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(4-(trifluoromethoxy)phenyl)cyclopropaneamine in the same manner as inStep G of Example 7.

MS (API+): [M+H]⁺407.1.

Example 1537-fluoro-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(5-fluoro-3-nitropyridin-2-yl)glycinate

To a solution of methyl glycinate hydrochloride (1.39 g) and2-chloro-5-fluoro-3-nitropyridine (2.00 g) in ethanol (35.9 mL) wasadded triethylamine (3.79 mL). The reaction mixture was stirredovernight at 80° C., and the solvent was evaporated under reducedpressure. The residue was diluted with ethyl acetate, and the mixturewas washed successively with water and saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate) to give the title compound (93.0 mg).

MS (API+): [M+H]⁺230.1.

B) 7-fluoro-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl N-(5-fluoro-3-nitropyridin-2-yl)glycinate (90.0mg) in tetrahydrofuran (6.66 mL) was added 5% platinum-carbon (10.0 mg).The reaction mixture was stirred at room temperature for 2 hr underhydrogen atmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure. The residue was dissolved inethanol (5.00 mL), and the mixture was stirred at 87° C. for 1 hr. Tothe reaction mixture was added 2 M hydrogen chloride/methanol solution(1.00 mL), the mixture was stirred overnight at 87° C., and the solventwas evaporated under reduced pressure. The residue was diluted withethyl acetate, and the mixture was neutralized with saturated aqueoussodium hydrogen carbonate solution, and extracted with ethyl acetate.The extract was washed with saturated brine, and the solvent wasevaporated under reduced pressure to give the title compound (39.1 mg).

MS (API+): [M+H]⁺168.1.

C)7-fluoro-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a mixture of 7-fluoro-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one (39.1mg) and triethylamine (99.0 μL) in a mixed solvent of tetrahydrofuran(2.00 mL) and N,N-dimethylacetamide (2.00 mL) was added a solution ofbis(trichloromethyl)carbonate (69.4 mg) in tetrahydrofuran (1.00 mL) at0° C. The reaction mixture was stirred at 0° C. for 2 hr, a mixture oftriethylamine (165 μL) and2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethanamine hydrochloride (318mg) in a mixed solvent of tetrahydrofuran (1.00 mL) andN,N-dimethylacetamide (2.00 mL) was added thereto at 0° C. The reactionmixture was stirred overnight at room temperature, water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed successively with water and saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate), and crystallized from hexane/ethyl acetate togive the title compound (10.1 mg).

MS (API+): [M+H]⁺429.1.

Example 154N-(2-methoxy-1-(4-(1H-pyrrol-1-yl)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-bromo-1-(4-iodophenyl)ethanone

The title compound was obtained from 1-(4-iodophenyl)ethanone in thesame manner as in Step F of Example 66.

¹H NMR (300 MHz, DMSO-d₆) δ 4.91 (2H, s), 7.72-7.80 (2H, m), 7.91-8.00(2H, m).

B) 1-(4-iodophenyl)-2-methoxyethanone

The title compound was obtained from 2-bromo-1-(4-iodophenyl)ethanone inthe same manner as in Step D of Example 63.

¹H NMR (300 MHz, DMSO-d₆) δ 3.35 (3H, s), 4.75 (2H, s), 7.63-7.73 (2H,m), 7.88-8.00 (2H, m).

C) 1-(4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethanone

The title compound was obtained from 1H-pyrrole and1-(4-iodophenyl)-2-methoxyethanone in the same manner as in Step A ofExample 147.

¹H NMR (300 MHz, DMSO-d₆) δ 3.37 (3H, s), 4.79 (2H, s), 6.29-6.41 (2H,m), 7.50-7.58 (2H, m), 7.71-7.82 (2H, m), 7.95-8.05 (2H, m).

D)N-(2-methoxy-1-(4-(1H-pyrrol-1-yl)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethanone in the same manner as inStep C of Example 1, Step B of Example 54 and Step G of Example 7.

MS (API+): [M+H]⁺406.2.

Example 1557-chloro-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(5-chloro-3-nitropyridin-2-yl)glycinate

To a solution of methyl N-(5-bromo-3-nitropyridin-2-yl)glycinate (400mg) in 1-methylpyrrolidin-2-one (13.8 mL) was added copper(I) chloride(410 mg). The reaction mixture was stirred at 150° C. for 2.5 hr undermicrowave irradiation, and water was added thereto. The insolublesubstance was filtered off, and the filtrate was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (hexane/ethyl acetate), and crystallized fromdiisopropyl ether to give the title compound (181 mg).

MS (API+): [M+H]⁺246.0.

B) 7-chloro-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl N-(5-chloro-3-nitropyridin-2-yl)glycinate (181mg) in tetrahydrofuran (12.5 mL) was added 5% platinum-carbon (20.0 mg).The reaction mixture was stirred at room temperature for 2 hr underhydrogen atmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure. The residue was dissolved inethanol (10.0 mL), and the solution was stirred overnight at 87° C. Tothe reaction mixture was added 2 M hydrogen chloride/methanol solution(1.00 mL), and the mixture was stirred at 87° C. for 10 min, and thesolvent was evaporated under reduced pressure. The residue was dilutedwith ethyl acetate, and the mixture was neutralized with saturatedaqueous sodium hydrogen carbonate solution, and extracted with ethylacetate. The extract was washed with saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure to give the title compound (132 mg).

MS (API+): [M+H]⁺184.0.

C)7-chloro-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from7-chloro-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one in the same manner asin Step C of Example 153.

MS (API+): [M+H]⁺445.1.

Example 156N-(2-methoxy-1-(4-(pyrrolidin-1-yl)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethanone in the same manner as inStep C of Example 1, Step E of Example 2 and Step G of Example 7.

MS (API+): [M+H]⁺410.3.

Example 157N-(2-methoxy-1-(4-(H-pyrrol-1-yl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethanone in the same manner as inStep C of Example 1, Step E of Example 2 and Step G of Example 7.

MS (API+): [M+H]⁺392.2.

Example 158N-(2-methoxy-1-(4-(pyrrolidin-1-yl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethanone in the same manner as inStep C of Example 1, Step B of Example 54 and Step G of Example 7.

MS (API+): [M+H]⁺396.2.

Example 159N-(1-(2,2-difluoro-1,3-benzodioxol-5-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(2,2-difluorobenzo[d][1,3]dioxol-5-yl)propan-1-ol

To a solution of 2,2-difluorobenzo[d][1,3]dioxol-5-carbaldehyde (2.35 g)in tetrahydrofuran (50 mL) was slowly added 3 M ethylmagnesiumbromide/tetrahydrofuran solution (6.30 mL) at 0° C. The reaction mixturewas stirred at room temperature for 16 hr, saturated ammonium chloridesolution was added thereto, and the mixture was extracted with ethylacetate. The extract was dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel chromatography (hexane/ethyl acetate) to give the titlecompound (2.36 g).

¹H NMR (300 MHz, DMSO-d₆) δ 0.81 (3H, t, J=7.3 Hz), 1.51-1.67 (2H, m),4.42-4.53 (1H, m), 5.27 (1H, d, J=4.5 Hz), 7.10-7.18 (1H, m), 7.27-7.36(2H, m).

B) 1-(2,2-difluorobenzo[d][1,3]dioxol-5-yl)propan-1-one

To a solution of 1-(2,2-difluorobenzo[d][1,3]dioxol-5-yl)propan-1-ol(2.36 g) in toluene (50 mL) was added manganese dioxide (2.36 g). Thereaction mixture was stirred at room temperature for 3 days, theinsoluble substance was filtered off, and the filtrate was concentratedunder reduced pressure. The residue was purified by silica gelchromatography (hexane/ethyl acetate) to give the title compound (0.492g).

¹H NMR (300 MHz, DMSO-d₆) δ 1.08 (3H, t, J=7.2 Hz), 3.05 (2H, q, J=7.1Hz), 7.55 (1H, d, J=8.3 Hz), 7.91 (1H, dd, J=8.5, 1.7 Hz), 7.96 (1H, d,J=1.7 Hz).

C)N-(1-(2,2-difluoro-1,3-benzodioxol-5-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(2,2-difluorobenzo[d][1,3]dioxol-5-yl)propan-1-one in the same manneras in Step C of Example 1, Step E of Example 2 and Step G of Example 7.

MS (API+): [M+H]⁺391.1.

Example 1607-methyl-2-oxo-N-(2-(1H-pyrazol-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-(1H-pyrazol-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethanone

A mixture of 1H-pyrazole (0.722 g), 60% sodium hydride (459 mg) andN,N-dimethylformamide (50 mL) was stirred at 0° C. for 10 min,2-bromo-1-(4-(trifluoromethoxy)phenyl)ethanone (2.5 g) was addedthereto, and the mixture was stirred at 0° C. for 20 min under nitrogenatmosphere. To the reaction mixture was added saturated aqueous ammoniumchloride solution, and the mixture was extracted with ethyl acetate. Theextract was washed with saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate) to give the title compound (598 mg).

MS (API+): [M+H]⁺271.1.

B)7-methyl-2-oxo-N-(2-(1H-pyrazol-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-(1H-pyrazol-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethanone in the samemanner as in Step D of Example 2, Step B of Example 15 and Step G ofExample 7.

MS (API+): [M+H]⁺461.2.

Example 161 Optically active7-methyl-2-oxo-N-(1-(4-(1H-pyrrol-1-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-methyl-2-oxo-N-(1-(4-(1H-pyrrol-1-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(244 mg) was resolved by HPLC (column: CHIRALPAK IC, 4.6 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: ethanol)to give the title compound having a shorter retention time (93.7 mg).

MS (API+): [M+H]⁺390.2.

Example 1627-methyl-2-oxo-N-(1-(5-(1H-pyrazol-1-yl)-2-thienyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 5-bromothiophene-2-carboxylic acidin the same manner as in Step A of Example 31, Step C of Example 134,Step B of Example 30, Step D of Example 2, Step B of Example 15 and StepG of Example 7.

MS (API+): [M+H]⁺397.0.

Example 163 Optically active7-methyl-2-oxo-N-(1-(4-(1H-pyrrol-1-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-methyl-2-oxo-N-(1-(4-(1H-pyrrol-1-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(244 mg) was resolved by HPLC (column: CHIRALPAK IC, 4.6 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: ethanol)to give the title compound having a longer retention time (93.0 mg).

MS (API+): [M+H]⁺390.2.

Example 1647-methyl-2-oxo-N-(2-(1H-1,2,4-triazol-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-bromo-1-(4-(trifluoromethoxy)phenyl)ethanone in the same manner as inStep A of Example 160, Step D of Example 2, Step B of Example 132 andStep G of Example 7.

MS (API+): [M+H]⁺462.2.

Example 1657-methyl-2-oxo-N-(1-(pyrazolo[1,5-a]pyridin-5-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) diethyl pyrazolo[1,5-a]pyridine-3,5-dicarboxylate

To a mixture of (aminooxy)(hydroxy)sulfane dioxide (15.0 g) and water(60 mL) was added saturated aqueous sodium hydrogen carbonate solutionat 0° C. to adjust the pH of the mixture to 9-10, and a mixture of ethylisonicotinate (10.0 g) and methanol (250 mL) was added thereto at 0° C.The reaction mixture was stirred overnight at 70° C.,N,N-dimethylformamide was added thereto, and the solvent was evaporatedunder reduced pressure. To the residue were added potassium carbonate(27.4 g), N,N-dimethylformamide (250 mL) and ethyl propynoate (7.14 g)at 0° C., and the reaction mixture was stirred at room temperature for 3hr. To the reaction mixture was added saturated brine, and the mixturewas extracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (hexane/ethyl acetate) to give the titlecompound (8.01 g).

MS (API+): [M+H]⁺263.1.

B) pyrazolo[1,5-a]pyridine-5-carboxylic acid

A mixture of diethyl pyrazolo[1,5-a]pyridine-3,5-dicarboxylate (6.7 g),conc. sulfuric acid (50 mL) and water (50 mL) was stirred overnight at100° C. The reaction mixture was cooled to room temperature, and the pHof the mixture was adjusted to about 3 with 8 M aqueous sodium hydroxidesolution. The obtained solid was collected by filtration, and washedwith water to give the title compound (3.15 g).

MS (API−): [M−H]⁻161.1.

C)7-methyl-2-oxo-N-(1-(pyrazolo[1,5-a]pyridin-5-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained frompyrazolo[1,5-a]pyridine-5-carboxylic acid in the same manner as in StepA of Example 31, Step B of Example 30, Step D of Example 2, Step B ofExample 132 and Step G of Example 7.

MS (API+): [M+H]⁺365.2.

Example 1667-methyl-N-(2-(oxetan-3-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) (2-oxo-2-(4-(trifluoromethoxy)phenyl)ethyl)triphenylphosphoniumbromide

To a solution of triphenylphosphine (6.29 g) in diethyl ether (20 mL)was slowly added a solution of2-bromo-1-(4-(trifluoromethoxy)phenyl)ethanone (6.68 g) in diethyl ether(10 mL) at room temperature. The reaction mixture was stirred at roomtemperature for 1 hr, and the resulting solid was collected byfiltration, washed with diethyl ether to give the title compound (9.47g).

MS (API+), found: 465.3.

B) 2-(oxetan-3-ylidene)-1-(4-(trifluoromethoxy)phenyl)ethanone

A mixture of(2-oxo-2-(4-(trifluoromethoxy)phenyl)ethyl)triphenylphosphonium bromide(6.54 g) and potassium tert-butoxide (1.35 g) in tetrahydrofuran (50 mL)was stirred at 0° C. for 15 min. The reaction mixture was stirred atroom temperature for 30 min, oxetan-3-one (721 mg) was added thereto,and the mixture was stirred overnight at 70° C. under argon atmosphere.The reaction mixture was cooled, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (2.18g).

¹H NMR (300 MHz, CDCl₃) δ 5.39-5.48 (2H, m), 5.64-5.72 (2H, m),6.77-6.85 (1H, m), 7.28-7.36 (2H, m), 7.93-8.02 (2H, m).

C) 2-(oxetan-3-yl)-1-(4-(trifluoromethoxy)phenyl)ethanone

To a solution of2-(oxetan-3-ylidene)-1-(4-(trifluoromethoxy)phenyl)ethanone (1.03 g) inethanol (35 mL) was added 10% palladium-carbon (containing 50% water,200 mg). The reaction mixture was stirred at room temperature for 1 hrunder hydrogen atmosphere, the insoluble substance was filtered off, andthe solvent was evaporated under reduced pressure. To a solution of theresidue (1.07 g) in acetonitrile (20.4 mL) was added Dess-Martinperiodinane (1.90 g) at room temperature. The reaction mixture wasstirred at room temperature for 1 hr, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (NH, hexane/ethyl acetate) to give the title compound(900 mg).

MS (API+): [M+H]⁺261.1.

D) N-hydroxy-2-(oxetan-3-yl)-1-(4-(trifluoromethoxy)phenyl)ethanimine

The title compound was obtained from2-(oxetan-3-yl)-1-(4-(trifluoromethoxy)phenyl)ethanone in the samemanner as in Step C of Example 1.

MS (API+): [M+H]⁺276.1.

E)7-methyl-N-(2-(oxetan-3-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution ofN-hydroxy-2-(oxetan-3-yl)-1-(4-(trifluoromethoxy)phenyl)ethanimine (275mg) in ethanol (5 mL) was added 5% palladium-carbon (containing 50%water, 120 mg) at room temperature. The reaction mixture was stirred atroom temperature for 5 hr under hydrogen atmosphere, and 20% palladiumhydroxide-carbon (30 mg) was added thereto. The reaction mixture wasstirred overnight at room temperature under hydrogen atmosphere, thecatalyst was filtered off, and the solvent was evaporated under reducedpressure to give2-(oxetan-3-yl)-1-(4-(trifluoromethoxy)phenyl)ethanamine (260 mg). To asolution of the obtained2-(oxetan-3-yl)-1-(4-(trifluoromethoxy)phenyl)ethanamine inN,N-dimethylformamide (5.06 mL) were added 4-nitrophenyl7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4-carboxylate (166 mg)and triethylamine (141 μL) at room temperature. The reaction mixture wasstirred at room temperature for 2 hr, water was added thereto, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) and thensilica gel column chromatography (NH, hexane/ethyl acetate) to give thetitle compound (92 mg).

MS (API+): [M+H]⁺451.2.

Example 1677-(difluoromethyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 6-hydroxy-5-nitronicotine acid

To a mixture of 2-chloro-5-methyl-3-nitropyridine (25.0 g) in conc.sulfuric acid (540 mL) was slowly added sodium dichromate dihydrate(64.8 g). The reaction mixture was stirred at room temperature for 4 hr,poured into crushed ice, and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The obtained solid was triturated with diisopropylether/hexane, and washed with diisopropyl ether/hexane to give the titlecompound (4.00 g).

¹H NMR (300 MHz, DMSO-d₆) δ 8.37 (1H, d, J=2.6 Hz), 8.64 (1H, d, J=2.6Hz), 13.33 (2H, brs).

B) 6-chloro-N-methoxy-N-methyl-5-nitronicotinamide

To a mixture of 6-hydroxy-5-nitronicotine acid (552 mg) and thionylchloride (6.57 mL) was added N,N-dimethylformamide (two drops). Thereaction mixture was stirred overnight at 70° C., and the solvent wasevaporated under reduced pressure. To a solution of the residue inN,N-dimethylacetamide (15.0 mL) was added N,O-dimethylhydroxylaminehydrochloride (322 mg) at 0° C. The reaction mixture was stirred at 0°C. for 2 hr, water was added thereto, and the mixture was extracted withethyl acetate. The extract was washed with saturated brine, and driedover anhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (647mg).

¹H NMR (300 MHz, DMSO-d₆) δ 3.28-3.36 (3H, m), 3.58 (3H, s), 8.77 (1H,d, J=2.1 Hz), 8.94 (1H, d, J=2.1 Hz).

C) methyl 2-((5-(methoxy(methyl)carbamoyl)-3-nitropyridin-2-yl)amino)acetate

The title compound was obtained from6-chloro-N-methoxy-N-methyl-5-nitronicotinamide in the same manner as inStep A of Example 1.

¹H NMR (300 MHz, DMSO-d₆) δ 3.28 (3H, s), 3.63 (3H, s), 3.67 (3H, s),4.37 (2H, d, J=5.7 Hz), 8.68-8.80 (2H, m), 9.00-9.12 (1H, m).

D) methyl 2-((5-formyl-3-nitropyridin-2-yl)amino)acetate

To a solution of methyl 2-((5-(methoxy(methyl)carbamoyl)-3-nitropyridin-2-yl)amino)acetate (250 mg) in tetrahydrofuran(8.38 mL) was slowly added 1.5 M diisobutylaluminium hydride/toluenesolution (1.12 mL) at −78° C. The reaction mixture was stirred at −78°C. for 1 hr under argon atmosphere, and methanol (170 μL) was addedthereto. The reaction mixture was stirred for 5 min, silica gel wasadded thereto, and the solvent was evaporated under reduced pressure.The residue was purified by column chromatography (hexane/ethyl acetate)to give the title compound (72 mg).

MS (API−): [M−H]⁻238.1.

E) methyl 2-((5-(difluoromethyl)-3-nitropyridin-2-yl)amino)acetate

To a solution of methyl 2-((5-formyl-3-nitropyridin-2-yl)amino)acetate(4.71 g) in acetonitrile (150 mL) was added N,N-diethylaminosulfurtrifluoride (20.8 mL) at room temperature. The reaction mixture wasstirred at room temperature for 2 hr, N,N-diethylaminosulfur trifluoride(20.8 mL) was added thereto at room temperature. The reaction mixturewas stirred at room temperature for 1 hr, saturated aqueous sodiumhydrogen carbonate solution was slowly added thereto at 0° C., and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (NH, hexane/ethyl acetate) to givethe title compound (2.78 g).

¹H NMR (300 MHz, CDCl₃) δ 3.81 (3H, s), 4.43 (2H, d, J=5.3 Hz),6.44-6.88 (1H, m), 8.51-8.61 (2H, m), 8.65 (1H, brs).

F) 7-(difluoromethyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

The title compound was obtained from methyl2-((5-(difluoromethyl)-3-nitropyridin-2-yl)amino)acetate in the samemanner as in Step B of Example 135.

¹H NMR (300 MHz, DMSO-d₆) δ 3.99 (2H, s), 6.63-7.12 (1H, m), 7.02 (1H,s), 7.27 (1H, s), 7.74-7.82 (1H, m), 10.55 (1H, s).

G)7-(difluoromethyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from7-(difluoromethyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one in the samemanner as in Step F of Example 1.

MS (API+): [M+H]⁺461.1.

Example 1687-methyl-2-oxo-N-(tetrahydro-2H-pyran-4-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) N-methoxy-N-methyltetrahydro-2H-pyran-4-carboxamide

To a solution of tetrahydro-2H-pyran-4-carboxylic acid (800 mg) inN,N-dimethylformamide (60.0 mL) were added 1-hydroxybenzotriazolemonohydrate (1.17 g), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimidehydrochloride (1.44 g), N,O-dimethylhydroxylamine hydrochloride (600 mg)and triethylamine (1.73 mL). The reaction mixture was stirred overnightat room temperature, water was added thereto, and the mixture wasextracted with ethyl acetate. The extract was washed successively withsaturated aqueous sodium hydrogen carbonate solution and saturatedbrine, dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure to give the title compound (831 mg).

MS (API+): [M+H]⁺174.3.

B) tetrahydro-2H-pyran-4-yl(4-(trifluoromethoxy)phenyl)methanone

To a solution of 1-bromo-4-(trifluoromethoxy)benzene (2.78 g) intetrahydrofuran (76.8 mL) was slowly added 1.6 M n-butyllithium/hexanesolution (7.20 mL) at −78° C. The reaction mixture was stirred at −78°C. for 30 min under nitrogen atmosphere, a solution ofN-methoxy-N-methyltetrahydro-2H-pyran-4-carboxamide (665 mg) intetrahydrofuran (1.00 mL) was added thereto at −78° C. The reactionmixture was stirred at room temperature for 2 hr under nitrogenatmosphere, saturated aqueous ammonium chloride solution was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed with saturated brine, and dried over anhydrous sodiumsulfate, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (hexane/ethylacetate) to give the title compound (812 mg).

MS (API+): [M+H]⁺275.1.

C)N-hydroxy-1-(tetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)methanimine

To a mixture oftetrahydro-2H-pyran-4-yl(4-(trifluoromethoxy)phenyl)methanone (690 mg)and hydroxylamine hydrochloride (713 mg) in ethanol (16.8 mL) was addedtriethylamine (1.42 mL) at room temperature. The reaction mixture wasstirred overnight at room temperature, and the solvent was evaporatedunder reduced pressure. The residue was diluted with ethyl acetate andwater, and the mixture was extracted with ethyl acetate. The extract waswashed with saturated brine, and dried over anhydrous sodium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (566 mg).

MS (API+): [M+H]⁺290.1.

D)1-(tetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)methanamine

To a solution ofN-hydroxy-1-(tetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)methanimine(566 mg) in tetrahydrofuran (25.0 mL) was added 1.1 Mborane-tetrahydrofuran complex/tetrahydrofuran solution (5.33 mL) atroom temperature. The reaction mixture was stirred overnight at 70° C.,1 M aqueous sodium hydroxide solution (19.6 mL) was added thereto, andthe mixture was stirred at 60° C. for 3 hr. To the reaction mixture wasadded saturated brine, and the mixture was extracted with ethyl acetate.The extract was washed with saturated brine, and dried over anhydroussodium sulfate, and the solvent was evaporated under reduced pressure togive the title compound (547 mg).

MS (API+): [M+H]⁺276.1.

E)7-methyl-2-oxo-N-(tetrahydro-2H-pyran-4-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(tetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)methanaminein the same manner as in Step B of Example 83.

MS (API+): [M+H]⁺465.2.

Example 169N-(2-(4-hydroxytetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)2-(4-hydroxytetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)ethanone

To a solution of diisopropylamine (3.36 mL) in tetrahydrofuran (100 mL)was slowly added 1.6 M n-butyllithium/hexane solution (15 mL) at −78° C.The reaction mixture was stirred at −78° C. for 30 min under argonatmosphere, and 4-trifluoromethoxyacetophenone (3.19 mL) was addedthereto at −78° C. The reaction mixture was stirred at −78° C. for 1 hrunder argon atmosphere, and tetrahydro-4H-pyran-4-one (1.85 mL) wasadded thereto at −78° C. The reaction mixture was stirred at −78° C. for1 hr under argon atmosphere, saturated aqueous ammonium chloridesolution was added thereto, and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (4.34g).

MS (API−): [M−H]⁻303.1.

B)N-(2-(4-hydroxytetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-(4-hydroxytetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)ethanonein the same manner as in Steps C-D of Example 1 and Step L of Example72-I.

MS (API+): [M+H]⁺495.1.

Example 1707-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methanone

To a solution of 1-bromo-4-(trifluoromethoxy)benzene (7.6 g) intetrahydrofuran (50 mL) was slowly added 1.6 M n-butyllithium/hexanesolution (19.7 mL) at −78° C. The reaction mixture was stirred at −78°C. for 40 min under nitrogen atmosphere, andN-methoxy-N-methyltetrahydrofuran-2-carboxamide (1.673 g) (obtained fromtetrahydrofuran-2-carboxylic acid in the same manner as in Step A ofExample 31) was added thereto at −78° C., and the reaction mixture wasstirred at room temperature for 1 hr under nitrogen atmosphere. To thereaction mixture was added saturated aqueous ammonium chloride solution,and the mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous magnesium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (2.49 g).

MS (API+): [M+H]⁺261.1.

B)7-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained fromtetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methanone in the samemanner as in Step D of Example 2, Step B of Example 132 and Step G ofExample 7.

MS (API+): [M+H]⁺451.2.

Example 171N-(2-hydroxy-1-(4-(trifluoromethoxy)phenyl)pentyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-(trifluoromethoxy)benzaldehyde inthe same manner as in Example 174.

MS (API+): [M+H]⁺453.2.

Example 172N-(3-((tert-butyl(diphenyl)silyl)oxy)-2,2-dimethyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl 3-((tert-butyl(diphenyl)silyl)oxy)-2,2-dimethylpropanoate

A mixture of methyl 3-hydroxy-2,2-dimethylpropanoate (18.3 g),tert-butyl(chloro)diphenylsilane (40.0 g), 1H-imidazole (12.3 g) andN,N-dimethylformamide (300 mL) was stirred overnight at roomtemperature, and the solvent was evaporated under reduced pressure. Tothe residue was added saturated brine, and the mixture was extractedwith ethyl acetate. The extract was washed with saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (50.6g).

¹H NMR (300 MHz, CDCl₃) δ 1.03 (9H, s), 1.20 (6H, s), 3.64 (2H, s), 3.67(3H, s), 7.31-7.47 (6H, m), 7.58-7.68 (4H, m).

B) 3-((tert-butyl(diphenyl)silyl)oxy)-2,2-dimethylpropanoic acid

A mixture of methyl3-((tert-butyl(diphenyl)silyl)oxy)-2,2-dimethylpropanoate (50.6 g), 8 Maqueous sodium hydroxide solution (150 mL) and tetrahydrofuran (150 mL)was stirred at 100° C. for 3 hr, and the pH of the mixture was adjustedto about 1 with 6 M hydrochloric acid, and the mixture was extractedwith ethyl acetate. The extract was washed with saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure to give the title compound (50.1 g).

MS (API−): [M−H]⁻355.2.

C)N-(3-((tert-butyl(diphenyl)silyl)oxy)-2,2-dimethyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from3-((tert-butyl(diphenyl)silyl)oxy)-2,2-dimethylpropanoic acid in thesame manner as in Step A of Example 170, Step D of Example 2, Step B ofExample 132 and Step G of Example 7.

MS (API+): [M+H]⁺691.4.

Example 173N-(2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)tert-butyl(2-(1,3-dioxoisoindolin-2-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate

A mixture oftert-butyl(2-amino-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate (762mg) and isobenzofuran-1,3-dione (423 mg) in toluene (20 mL) was heatedat reflex using Dean-Stark for 16 hr, and the solvent was evaporatedunder reduced pressure. The obtained solid was triturated with ethylacetate, collected by filtration, and washed with ethyl acetate to givethe title compound (399 mg).

MS (API+), found: 351.1.

B) 2-(2-amino-2-(4-(trifluoromethoxy)phenyl)ethyl)isoindoline-1,3-dionehydrochloride

The title compound was obtained fromtert-butyl(2-(1,3-dioxoisoindolin-2-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamatein the same manner as in Step E of Example 18.

¹H NMR (300 MHz, DMSO-d₆) δ 3.89-4.01 (1H, m), 4.03-4.16 (1H, m), 4.67(1H, t, J=6.9 Hz), 7.41-7.51 (2H, m), 7.64-7.74 (2H, m), 7.87 (4H, d,J=2.8 Hz), 8.65 (3H, brs).

C)N-(2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-(2-amino-2-(4-(trifluoromethoxy)phenyl)ethyl) isoindoline-1,3-dionehydrochloride in the same manner as in Step L of Example 72-I.

MS (API+): [M+H]⁺526.2.

Example 174N-(2-cyclopropyl-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) tert-butyl(cyano(4-(trifluoromethoxy)phenyl)methyl)carbamate

To 2 M ammonia/methanol solution (112 mL) of4-(trifluoromethoxy)benzaldehyde (10.6 g) was added titanium(IV)tetraisopropoxide (16.3 mL) at 0° C. The reaction mixture was stirred at0° C. for 15 min, trimethylsilyl cyanide (11.2 mL) was added thereto,and the reaction mixture was stirred at room temperature for 20 hr, andconcentrated to about ¼ of volume under reduced pressure, saturatedaqueous sodium hydrogen carbonate solution was added thereto, theinsoluble substance was filtered off using Celite, and the filtrate wasextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. To a solution ofthe residue in tetrahydrofuran (300 mL) were added di-tert-butyldicarbonate (12.94 mL) and triethylamine (9.32 mL). The reaction mixturewas stirred at 45° C. for 16 hr, water was added thereto, and themixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate) to give the title compound (9.39 g).

MS (API+): [M+H]⁺317.1.

B)tert-butyl(2-amino-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate

To a mixture oftert-butyl(cyano(4-(trifluoromethoxy)phenyl)methyl)carbamate (3.00 g)and potassium carbonate (1.31 g) in dimethyl sulfoxide (70 mL) was added35% aqueous hydrogen peroxide (1.66 mL) at 0° C. The reaction mixturewas stirred at room temperature for 3 hr, water was added thereto, andthe mixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate) to give the title compound (2.44 g).

¹H NMR (300 MHz, CDCl₃) δ 1.41 (9H, s), 5.11-5.28 (1H, m), 5.48 (1H,brs), 5.68 (1H, brs), 5.78 (1H, brs), 7.18-7.25 (2H, m), 7.40-7.47 (2H,m).

C)tert-butyl(2-(methoxy(methyl)amino)-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate

To a solution oftert-butyl(2-amino-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate(2.44 g) in methanol (70 mL) was added 8 M aqueous sodium hydroxidesolution (1.8 mL), the reaction mixture was heated at reflex for 20 hr.The solvent was evaporated under reduced pressure, the pH of the residuewas adjusted to 3-4 with 1 M hydrochloric acid, and the mixture wasextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. A mixture of theobtained residue, N,O-dimethylhydroxylamine hydrochloride (0.783 g),triethylamine (1.32 mL), 1-hydroxybenzotriazole monohydrate (1.45 g) and1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (1.82 g) inN,N-dimethylformamide (30 mL) was stirred at room temperature for 3 hr,water was added thereto, and the mixture was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (hexane/ethyl acetate) to give the titlecompound (1.39 g).

¹H NMR (300 MHz, CDCl₃) δ 1.42 (9H, s), 3.19 (3H, s), 3.51 (3H, s),5.63-5.91 (2H, m), 7.14-7.22 (2H, m), 7.37-7.45 (2H, m).

D)tert-butyl(2-cyclopropyl-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate

To a solution oftert-butyl(2-(methoxy(methyl)amino)-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate(685 mg) in tetrahydrofuran (15 mL) was added 0.7 M cyclopropylmagnesiumbromide/tetrahydrofuran solution (7.76 mL) at 0° C. The reaction mixturewas stirred at room temperature for 20 hr, 1 M hydrochloric acid wasadded thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (486mg).

¹H NMR (300 MHz, CDCl₃) δ 0.75-0.86 (1H, m), 0.90-1.05 (2H, m),1.08-1.17 (1H, m), 1.40 (9H, s), 1.79-1.90 (1H, m), 5.48 (1H, d, J=6.4Hz), 5.92-6.04 (1H, m), 7.18-7.25 (2H, m), 7.33-7.41 (2H, m).

E)N-(2-cyclopropyl-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

A mixture oftert-butyl(2-cyclopropyl-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate(200 mg) and 4 M hydrogen chloride/ethyl acetate solution (5 mL) wasstirred at room temperature for 1 hr, and the solvent was evaporatedunder reduced pressure. To a mixture of the residue and 4-nitrophenyl2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (160 mg) inN,N-dimethylformamide (5 mL) was added triethylamine (0.213 mL). Thereaction mixture was stirred at room temperature for 20 hr, water wasadded thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate), and recrystallized fromhexane/ethyl acetate to give the title compound (143 mg).

MS (API+): [M+H]⁺435.1.

Example 175N-(2-cyclopropyl-2-hydroxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a mixture ofN-(2-cyclopropyl-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(126 mg) in a mixed solvent of methanol (3 mL) and tetrahydrofuran (1mL) was added sodium borohydride (13.2 mg) at 0° C. The reaction mixturewas stirred at room temperature for 3 hr, water was added thereto, andthe mixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was crystallized from hexane/ethyl acetate to givethe title compound (87.2 mg).

MS (API+): [M+H]⁺ 437.2.

Example 1767-methyl-2-oxo-N-(2-(tetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 4-(2-azido-2-(4-(trifluoromethoxy)phenyl)ethyl)tetrahydro-2H-pyran

To a solution of2-(4-hydroxytetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)ethanone(304 mg) in pyridine (5 mL) was added thionyl chloride (102 μL) at 0° C.The reaction mixture was stirred at 0° C. for 10 min, water was addedthereto at 0° C., and the mixture was extracted with ethyl acetate. Theextract was washed with saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. A mixture of the residue (286 mg) and 10% palladium-carbon(containing 50% water, 60 mg) in ethanol (5 mL) was stirred at roomtemperature for 2 hr under hydrogen atmosphere. The insoluble substancewas filtered off, and the filtrate was concentrated under reducedpressure. To a solution of the residue (290 mg) in tetrahydrofuran (5mL) were added triphenylphosphine (315 mg), diphenylphosphoryl azide(259 μL) and 1.9 M diisopropyl azodicarboxylate/toluene solution (632μL) at room temperature. The reaction mixture was stirred at roomtemperature for 30 min, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate) to give the title compound (274 mg).

¹H NMR (300 MHz, CDCl₃) δ 1.20-1.44 (2H, m), 1.52-1.72 (4H, m),1.73-1.87 (1H, m), 3.30-3.43 (2H, m), 3.89-4.01 (2H, m), 4.48-4.59 (1H,m), 7.19-7.46 (4H, m).

B)7-methyl-2-oxo-N-(2-(tetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

A mixture of4-(2-azido-2-(4-(trifluoromethoxy)phenyl)ethyl)tetrahydro-2H-pyran (274mg) and 10% palladium-carbon (containing 50% water, 92 mg) in ethanol(4.4 mL) was stirred at room temperature for 1 hr under hydrogenatmosphere. The catalyst was filtered off, and the solvent wasevaporated under reduced pressure to give2-(tetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)ethanamine(254 mg). To a mixture of 4-nitrophenyl7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (144mg) in N,N-dimethylformamide (2.19 mL) were added2-(tetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)ethanamine(254 mg) obtained above and triethylamine (122 μL) at room temperature.The reaction mixture was stirred overnight at room temperature, waterwas added thereto, and the mixture was extracted with ethyl acetate. Theextract was washed with saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(NH, hexane/ethyl acetate) to give the title compound (184 mg).

MS (API+): [M+H]⁺ 479.2.

Example 1772-oxo-N-(2-oxo-1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution ofN-(2-(methoxy(methyl)amino)-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(290 mg) in tetrahydrofuran (7 mL) was added 1 M methylmagnesiumbromide/tetrahydrofuran solution (7.0 mL) at 0° C. The reaction mixturewas stirred at room temperature for 20 hr, 1 M hydrochloric acid wasadded thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate), and recrystallized fromhexane/ethyl acetate to give the title compound (174 mg).

MS (API+): [M+H]⁺ 409.1.

Example 1788-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 2-chloro-4-methoxy-3-nitropyridinein the same manner as in Steps A-B of Example 1 and Steps C-D of Example19.

MS (API+): [M+H]⁺441.2.

Example 179N-(2-hydroxy-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-oxo-N-(2-oxo-1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidein the same manner as in Example 175.

MS (API+): [M+H]⁺ 411.1.

Example 1802-oxo-N-(2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethanol

To a solution of 1-bromo-4-(trifluoromethoxy)benzene (10.1 g) intetrahydrofuran (90 mL) was slowly added 1.6 M n-butyllithium/hexanesolution (28.7 mL) at −78° C. The reaction mixture was stirred at −78°C. for 30 min, a solution of 2,2,2-trifluoro-1-(piperidin-1-yl)ethanone(9.07 g) in tetrahydrofuran (10 mL) was slowly added thereto. Thereaction mixture was stirred at −78° C. for 1.5 hr, saturated aqueousammonium chloride solution was added thereto, and the mixture wasextracted with diethyl ether. The extract was dried over anhydroussodium sulfate, and the solvent was evaporated under reduced pressure togive a crude product of2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethanone. To a solution ofthe obtained crude product (11.9 g) in ethanol (80 mL) was slowly addedsodium borohydride (3.49 g) under ice-cooling. The reaction mixture wasstirred at room temperature for 16 hr, and the ethanol was evaporatedunder reduced pressure. To the residue was added 1 M hydrochloric acid,and the mixture was extracted with ethyl acetate. The extract was washedsuccessively with 1 M hydrochloric acid and saturated brine, dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel chromatography(hexane/ethyl acetate) to give the title compound (9.57 g).

MS (API−): [M−H]⁻259.0.

B) 2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethyl methanesulfonate

To a mixture of 2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethanol(9.57 g) and triethylamine (7.69 mL) in tetrahydrofuran (100 mL) wasslowly added methanesulfonyl chloride (3.42 mL) under ice-cooling. Thereaction mixture was stirred at room temperature for 1.5 hr, water wasadded thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure to give the title compound (10.7 g).

¹H NMR (300 MHz, DMSO-d₆) δ 3.33 (3H, s), 6.62 (1H, q, J=6.8 Hz),7.48-7.58 (2H, m), 7.68-7.78 (2H, m).

C) 1-(1-azido-2,2,2-trifluoroethyl)-4-(trifluoromethoxy)benzene

To a solution of 2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethylmethanesulfonate (10.7 g) in N,N-dimethylformamide (100 mL) was addedsodium azide (5.15 g) at room temperature. The reaction mixture wasstirred at 100° C. for 24 hr, and then at room temperature for 2 days.To the reaction mixture was added water, and the mixture was extractedwith diethyl ether. The extract was washed successively with water andsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel chromatography (hexane/ethyl acetate) to give the titlecompound (5.12 g).

¹H NMR (300 MHz, CDCl₃) δ 4.94 (1H, q, J=6.8 Hz), 7.26-7.33 (2H, m),7.43-7.53 (2H, m).

D) 2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethanamine

To a solution of1-(1-azido-2,2,2-trifluoroethyl)-4-(trifluoromethoxy)benzene (4.92 g) inmethanol (30 mL) was added 10% palladium-carbon (containing 50% water, 1g). The reaction mixture was stirred at room temperature for 2 hr underhydrogen atmosphere, the insoluble substance was filtered off, and thefiltrate was concentrated under reduced pressure. To the residue wasadded brine, and the mixture was extracted with diethyl ether. Theextract was washed with saturated brine, and dried over anhydrous sodiumsulfate, solvent was evaporated under reduced pressure to give the titlecompound (4.31 g).

¹H NMR (300 MHz, DMSO-d₆) δ 2.57 (2H, brs), 4.49-4.68 (1H, m), 7.34-7.44(2H, m), 7.58-7.68 (2H, m).

E)2-oxo-N-(2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethanamine in the samemanner as in Steps F-I of Example 63.

MS (API+): [M+H]⁺435.1.

Example 1817-methyl-2-oxo-N-(2-(pyridin-3-yloxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-((5-bromopyridin-3-yl)oxy)-1-(4-(trifluoromethoxy)phenyl)ethanone

To a solution of 5-bromopyridin-3-ol (5 g) in N,N-dimethylformamide (100mL) was added 60% sodium hydride (1.72 g) at 0° C. The reaction mixturewas stirred at 0° C. for 30 min,2-bromo-1-(4-(trifluoromethoxy)phenyl)ethanone (9.76 g) was addedthereto at 0° C. The reaction mixture was stirred at room temperaturefor 3 hr, and added to saturated aqueous ammonium chloride solution, andthe mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous magnesium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate), andthe obtained solid was washed with hexane to give the title compound(7.78 g).

MS (API+): [M+H]⁺376.0.

B)7-methyl-2-oxo-N-(2-(pyridin-3-yloxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-((5-bromopyridin-3-yl)oxy)-1-(4-(trifluoromethoxy)phenyl)ethanone inthe same manner as in Step D of Example 2, Step B of Example 132 andStep G of Example 7.

MS (API+): [M+H]⁺488.2.

Example 182N-(2-hydroxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-((5-bromopyridin-3-yl)oxy)-1-(4-(trifluoromethoxy)phenyl)ethanone inthe same manner as in Step D of Example 2, Step B of Example 132 andStep G of Example 7.

MS (API+): [M+H]⁺ 411.1.

Example 183N-(1-(3,5-difluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 5-(1-ethoxyvinyl)-1,3-difluoro-2-(trifluoromethoxy)benzene

A mixture of 5-bromo-1,3-difluoro-2-(trifluoromethoxy)benzene (5.00 g),tributyl(l-ethoxyvinyl)stannane (7.17 g),bis(triphenylphosphine)dichloropalladium(II) (0.38 g) and toluene (100mL) was stirred overnight at 100° C. under nitrogen atmosphere, and 1 Mhydrochloric acid (20 mL) was added thereto. The reaction mixture wasstirred at room temperature for 3 hr, saturated brine was added thereto,and the mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, dried over anhydrous magnesium sulfate, andpurified by silica gel column chromatography (NH, hexane/ethyl acetate)to give the title compound (4.24 g).

¹H NMR (300 MHz, CDCl₃) δ 1.42 (3H, t, J=7.0 Hz), 3.91 (2H, q, J=6.8Hz), 4.31 (1H, d, J=3.4 Hz), 4.67 (1H, d, J=3.0 Hz), 7.21-7.35 (2H, m).

B) 1-(3,5-difluoro-4-(trifluoromethoxy)phenyl)ethanone

A mixture of 5-(1-ethoxyvinyl)-1,3-difluoro-2-(trifluoromethoxy)benzene(4.24 g), 6 M hydrochloric acid (15 mL), acetone (50 mL) and water (15mL) was stirred at room temperature for 5 hr, and the mixture wasextracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure to give the title compound (3.51 g).

¹H NMR (300 MHz, CDCl₃) δ 2.60 (3H, s), 7.56-7.67 (2H, m).

C)N-(1-(3,5-difluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(3,5-difluoro-4-(trifluoromethoxy)phenyl)ethanone in the same manneras in Step A of Example 143, Step D of Example 63, Step D of Example 2,Step B of Example 15 and Step G of Example 7.

MS (API+): [M+H]⁺ 461.1.

Example 184N-(3-hydroxy-2,2-dimethyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a mixture ofN-(3-((tert-butyl(diphenyl)silyl)oxy)-2,2-dimethyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(90 mg) and acetic acid (23.5 mg) in tetrahydrofuran (5 mL) was added 1M tetra-n-butylammonium fluoride/tetrahydrofuran solution (0.391 mL).The reaction mixture was stirred overnight at room temperature, and 1 Mtetra-n-butylammonium fluoride/tetrahydrofuran solution (0.782 mL) wasadded. The reaction mixture was stirred at room temperature for 2 hr,and then overnight at 50° C. To the reaction mixture was added saturatedbrine, and the mixture was extracted with ethyl acetate. The extract waswashed with saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (43.2 mg).

MS (API+): [M+H]⁺453.2.

Example 185N-(2-fluoro-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl(4-(trifluoromethoxy)phenyl)acetate

To a solution of (4-(trifluoromethoxy)phenyl)acetic acid (5.00 g) inmethanol (31.3 mL) was added conc. sulfuric acid (237 μL). The reactionmixture was stirred at 70° C. for 3 hr, and concentrated under reducedpressure to about 10 mL. To the residue was added water, and the mixturewas extracted with ethyl acetate. The extract was washed successivelywith saturated aqueous sodium hydrogen carbonate solution and saturatedbrine, dried over anhydrous sodium sulfate, and the solvent wasevaporated under reduced pressure to give the title compound (5.23 g).

¹H NMR (300 MHz, CDCl₃) δ 3.63 (2H, s), 3.71 (3H, s), 7.17 (2H, d, J=7.9Hz), 7.27-7.37 (2H, m).

B) 2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-ol

To a solution of methyl(4-(trifluoromethoxy)phenyl)acetate (5.23 g) intetrahydrofuran (200 mL) was slowly added 1 M methylmagnesiumbromide/tetrahydrofuran solution (55.8 mL). The reaction mixture wasstirred overnight at room temperature, 1 M methylmagnesiumbromide/tetrahydrofuran solution (55.8 mL) was added thereto, and themixture was stirred at room temperature for 2 hr. To the reactionmixture was added saturated aqueous ammonium chloride solution at 0° C.,and the mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (2.65 g).

¹H NMR (300 MHz, CDCl₃) δ 1.23 (6H, s), 1.30 (1H, s), 2.77 (2H, s),7.11-7.19 (2H, m), 7.21-7.29 (2H, m).

C) 1-(2-fluoro-2-methylpropyl)-4-(trifluoromethoxy)benzene

To 2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-ol (2.55 g) was addedN,N-diethylaminosulfur trifluoride (2.88 mL) at 0° C., and the reactionmixture was stirred overnight at room temperature. The reaction mixturewas diluted with diethyl ether, water was added thereto at 0° C., andthe mixture was extracted with diethyl ether. The extract was washedsuccessively with saturated aqueous sodium hydrogen carbonate solutionand saturated brine, dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane) to give the title compound(1.59 g).

¹H NMR (300 MHz, CDCl₃) δ 1.30 (3H, s), 1.37 (3H, s), 2.83-2.97 (2H, m),7.09-7.18 (2H, m), 7.20-7.28 (2H, m).

D) 1-(1-bromo-2-fluoro-2-methylpropyl)-4-(trifluoromethoxy)benzene

A mixture of 1-(2-fluoro-2-methylpropyl)-4-(trifluoromethoxy)benzene(1.59 g), N-bromosuccinimide (1.59 g) and2,2′-azobis(2-methylpropionitrile) (113 mg) in trifluoromethylbenzene(33.7 mL) was stirred at 80° C. for 2 hr. To the reaction mixture wasadded hexane, the insoluble substance was filtered off, and the filtratewas concentrated under reduced pressure. The residue was purified bysilica gel column chromatography (hexane) to give the title compound(1.66 g).

¹H NMR (300 MHz, CDCl₃) δ 1.48 (3H, d, J=3.8 Hz), 1.55 (3H, d, J=4.9Hz), 4.92 (1H, d, J=17.3 Hz), 7.18 (2H, d, J=8.3 Hz), 7.49 (2H, d, J=8.7Hz)

E) 1-(1-azido-2-fluoro-2-methylpropyl)-4-(trifluoromethoxy)benzene

A mixture of1-(1-bromo-2-fluoro-2-methylpropyl)-4-(trifluoromethoxy)benzene (1.56 g)and sodium azide (1.65 g) in N,N-dimethylformamide (33.1 mL) was stirredovernight at 100° C., water was added thereto, and the mixture wasextracted with diethyl ether. The extract was washed successively withwater and saturated brine, and dried over anhydrous sodium sulfate, andthe solvent was evaporated under reduced pressure to give the titlecompound (1.13 g).

¹H NMR (300 MHz, CDCl₃) δ 1.27-1.34 (3H, m), 1.35-1.42 (3H, m), 4.55(1H, d, J=13.9 Hz), 7.18-7.26 (2H, m), 7.39 (2H, d, J=8.7 Hz).

F) 2-fluoro-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-1-amine

A mixture of1-(1-azido-2-fluoro-2-methylpropyl)-4-(trifluoromethoxy)benzene (1.13 g)and 10% palladium-carbon (containing 50% water, 110 mg) in methanol (7mL) was stirred at room temperature for 1 hr under hydrogen atmosphere,and the catalyst was filtered off. To the filtrate was added saturatedbrine, and the mixture was extracted with diethyl ether. The extract waswashed successively with water and saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure to give the title compound (971 mg).

MS (API+): [M+H]⁺252.1.

G)N-(2-fluoro-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-fluoro-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-1-amine in thesame manner as in Step E of Example 168.

MS (API+): [M+H]⁺427.1.

Example 1862-oxo-N-(1-(4-(2H-1,2,3-triazol-2-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(4-(2H-1,2,3-triazol-2-yl)phenyl)propan-1-one

A mixture of2-di-tert-butylphosphino-3,4,5,6-tetramethyl-2′,4′,6′-triisopropyl-1,1′-biphenyl(181 mg) and tris(dibenzylideneacetone)dipalladium(0) (172 mg) intoluene (4 mL) was stirred at 120° C. for 3 min under argon atmosphere.The mixture was added to a mixture of 2H-1,2,3-triazole (389 mg),1-(4-bromophenyl)propan-1-one (1 g) and tripotassium phosphate (1.99 g)in toluene (15 mL) at room temperature under argon atmosphere. Thereaction mixture was heated at reflex for 16 hr under argon atmosphere,water was added thereto, and the mixture was extracted with ethylacetate. The extract was dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (858 mg).

¹H NMR (300 MHz, DMSO-d₆) δ 1.11 (3H, t, J=7.2 Hz), 3.09 (2H, q, J=7.2Hz), 8.16 (4H, s), 8.21 (2H, s).

B)2-oxo-N-(1-(4-(2H-1,2,3-triazol-2-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(4-(2H-1,2,3-triazol-2-yl)phenyl)propan-1-one in the same manner as inStep C of Example 1, Step B of Example 54 and Step B of Example 53.

MS (API+): [M+H]⁺378.2.

Example 187N-(2-fluoro-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-fluoro-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-1-amine in thesame manner as in Step E of Example 168.

MS (API+): [M+H]⁺441.2.

Example 188N-(1-(3-fluoro-4-(pyrrolidin-1-yl)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-bromo-1-(4-bromo-3-fluorophenyl)ethanone

The title compound was obtained from 1-(4-bromo-3-fluorophenyl)ethanonein the same manner as in Step F of Example 66.

¹H NMR (300 MHz, DMSO-d₆) δ 4.96 (2H, s), 7.77 (1H, dd, J=8.3, 1.9 Hz),7.90-8.00 (2H, m).

B) 1-(4-bromo-3-fluorophenyl)-2-methoxyethanone

The title compound was obtained from2-bromo-1-(4-bromo-3-fluorophenyl)ethanone in the same manner as in StepD of Example 63.

¹H NMR (300 MHz, CDCl₃) δ 3.50 (3H, s), 4.62 (2H, s), 7.56-7.76 (3H, m).

C) 2-(4-bromo-3-fluorophenyl)-2-(methoxymethyl)-1,3-dioxolane

A mixture of 1-(4-bromo-3-fluorophenyl)-2-methoxyethanone (1.01 g),p-toluenesulfonic acid monohydrate (77 mg) and 1,2-ethanediol (506 mg)in toluene (20 mL) heated at reflex using Dean-Stark for 5 hr, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (NH, hexane/ethyl acetate) to givethe title compound (1.00 g).

¹H NMR (300 MHz, DMSO-d₆) δ 3.24 (3H, s), 3.54 (2H, s), 3.73-3.87 (2H,m), 3.95-4.09 (2H, m), 7.21 (1H, dd, J=8.2, 2.0 Hz), 7.33 (1H, dd,J=9.8, 2.1 Hz), 7.70 (1H, dd, J=8.2, 7.3 Hz).

D)N-(1-(3-fluoro-4-(pyrrolidin-1-yl)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-(4-bromo-3-fluorophenyl)-2-(methoxymethyl)-1,3-dioxolane in the samemanner as in Step A of Example 147, Step C of Example 1, Step B ofExample 54 and Step B of Example 53.

MS (API+): [M+H]⁺428.2.

Example 189N-(1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from2-(4-bromo-3-fluorophenyl)-2-(methoxymethyl)-1,3-dioxolane in the samemanner as in Step A of Example 147, Step C of Example 1, Step B ofExample 54 and Step B of Example 53.

MS (API+): [M+H]⁺424.2.

Example 1908-(2-hydroxypropan-2-yl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-chloro-3-nitroisonicotine acid

The title compound was obtained from 2-chloro-4-methyl-3-nitropyridinein the same manner as in Step A of Example 167.

MS (API−): [M−H]⁻201.0.

B) methyl 2-chloro-3-nitroisonicotinate

To a mixture of 2-chloro-3-nitroisonicotine acid (2.03 g) and thionylchloride (21.9 mL) was added N,N-dimethylformamide (two drops). Thereaction mixture was stirred at 70° C. for 15 min, and the solvent wasevaporated under reduced pressure. To the residue was added methanol (10mL) at 0° C., and the reaction mixture was stirred at 0° C. for 10 min,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (2.15 g).

¹H NMR (300 MHz, CDCl₃) δ 3.97 (3H, s), 7.86 (1H, d, J=5.1 Hz), 8.68(1H, d, J=4.9 Hz).

C) methyl 4-((2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamoyl)-2-oxo-1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-8-carboxylate

The title compound was obtained from methyl2-chloro-3-nitroisonicotinate in the same manner as in Steps A-B ofExample 1 and Steps C-D of Example 19.

MS (API+): [M+H]⁺469.2.

D)8-(2-hydroxypropan-2-yl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of methyl4-((2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamoyl)-2-oxo-1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-8-carboxylate(234 mg) in tetrahydrofuran (5 mL) was added 1 M methylmagnesiumbromide/tetrahydrofuran solution (10 mL) at room temperature. Thereaction mixture was stirred at room temperature for 20 hr, 1 Mhydrochloric acid was added thereto at 0° C., and the mixture wasextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate), andrecrystallized from hexane/ethyl acetate to give the title compound (47mg).

MS (API+): [M+H]⁺ 469.2.

Example 1918-acetyl-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of methyl4-((2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamoyl)-2-oxo-1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-8-carboxylate(234 mg) in tetrahydrofuran (5 mL) was added 1 M methylmagnesiumbromide/tetrahydrofuran solution (10 mL) at room temperature. Thereaction mixture was stirred at room temperature for 20 hr, 1 Mhydrochloric acid was added thereto at 0° C., and the mixture wasextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate), andrecrystallized from hexane/ethyl acetate to give the title compound (22mg).

MS (API+): [M+H]⁺ 453.1.

Example 1928-(hydroxymethyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 4-((2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamoyl)-2-oxo-1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-8-carboxylicacid

To a mixture of methyl4-((2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamoyl)-2-oxo-1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-8-carboxylate(468 mg) in tetrahydrofuran (10 mL) and methanol (2.0 mL) was added 1 Maqueous sodium hydroxide solution (2.0 mL). The reaction mixture wasstirred for 1 hr, and neutralized with 1 M hydrochloric acid, and themixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reduced pressureto give the title compound (452 mg).

MS (API+): [M+H]⁺ 455.1.

B)8-(hydroxymethyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of 4-((2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamoyl)-2-oxo-1,2,3,4-tetrahydropyrido[2,3-b]pyrazine-8-carboxylicacid (445 mg) in tetrahydrofuran (10 mL) were added isobutylchloroformate (0.153 mL) and triethylamine (0.205 mL). The reactionmixture was stirred at room temperature for 1 hr, and the insolublesubstance was filtered off. To the filtrate was added an aqueoussolution (1 mL) of sodium borohydride (74.1 mg). The reaction mixturewas stirred for 1 hr, water was added thereto, and the mixture wasextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate), andrecrystallized from hexane/ethyl acetate to give the title compound (13mg).

MS (API+): [M+H]⁺ 441.2.

Example 193N-(2-ethyl-2-hydroxy-1-(4-(trifluoromethoxy)phenyl)butyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) tert-butyl(2-oxo-1-(4-(trifluoromethoxy)phenyl)butyl)carbamate

To a solution oftert-butyl(2-(methoxy(methyl)amino)-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)carbamate(355 mg) in tetrahydrofuran (20 mL) was added 3 M ethylmagnesiumbromide/diethyl ether solution (5.0 mL) at room temperature. Thereaction mixture was stirred at room temperature for 20 hr, 1 Mhydrochloric acid was added thereto, and the mixture was extracted withethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (254 mg).

¹H NMR (300 MHz, CDCl₃) δ 1.00 (3H, t, J=7.3 Hz), 1.40 (9H, s),2.29-2.49 (2H, m), 5.30 (1H, d, J=6.0 Hz), 5.91-6.01 (1H, m), 7.17-7.24(2H, m), 7.30-7.37 (2H, m).

B)tert-butyl(2-ethyl-2-hydroxy-1-(4-(trifluoromethoxy)phenyl)butyl)carbamate

To a solution oftert-butyl(2-oxo-1-(4-(trifluoromethoxy)phenyl)butyl)carbamate (320 mg)in tetrahydrofuran (10 mL) was added 3 M ethylmagnesium bromide/diethylether solution (5.0 mL) at 0° C. The reaction mixture was stirred atroom temperature for 20 hr, 1 M hydrochloric acid was added thereto at0° C., and the mixture was extracted with ethyl acetate. The extract waswashed successively with water and saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (170mg).

MS (API−): [M−H]⁻ 376.2.

C)N-(2-ethyl-2-hydroxy-1-(4-(trifluoromethoxy)phenyl)butyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Totert-butyl(2-ethyl-2-hydroxy-1-(4-(trifluoromethoxy)phenyl)butyl)carbamate(170 mg) was added 4 M hydrogen chloride/ethyl acetate solution (5 mL)at room temperature. The reaction mixture was stirred at roomtemperature for 20 min, and the solvent was evaporated under reducedpressure. To a mixture of the residue and 4-nitrophenyl2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (128 mg) inN,N-dimethylformamide (5 mL) was added triethylamine (0.170 mL). Thereaction mixture was stirred at room temperature for 20 hr, water wasadded thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate), and recrystallized fromhexane/ethyl acetate to give the title compound (161 mg).

MS (API+): [M+H]⁺ 453.2.

Example 194N-(2-amino-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution ofN-(2-(1,3-dioxo-1,3-dihydro-2H-isoindol-2-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(285 mg) in ethanol (15 mL) was added hydrazine monohydrate (0.211 mL)at room temperature. The reaction mixture was stirred at 80° C. for 3hr, and the solvent was evaporated under reduced pressure. To theresidue was added 1 M aqueous sodium hydroxide solution, and the mixturewas purified by styrene/divinyl benzene synthetic adsorbent (HP-20,mobile phase: water-acetonitrile). The residue was purified bypreparative HPLC (C18, mobile phase: water (10 mM, containingNH₄HCO₃)/acetonitrile), and the obtained fraction was concentrated underreduced pressure. The obtained solid was triturated with hexane/ethylacetate, collected by filtration, and washed with hexane/ethyl acetateto give the title compound (151 mg).

MS (API+): [M+H]⁺396.1.

Example 195N-((4-bromo-2-fluorophenyl)(4-(trifluoromethoxy)phenyl)methyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 4-bromo-2-fluoro-N-methoxy-N-methylbenzamide

The title compound was obtained from 4-bromo-2-fluorobenzoic acid in thesame manner as in Step A of Example 31.

MS (API+): [M+H]⁺262.0.

B) (4-bromo-2-fluorophenyl)(4-(trifluoromethoxy)phenyl)methanone

To a solution of 4-bromo-2-fluoro-N-methoxy-N-methylbenzamide (10.8 g)in tetrahydrofuran (150 mL) was added 0.5 M(4-(trifluoromethoxy)phenyl)magnesium bromide/tetrahydrofuran solution(165 mL) at room temperature. The reaction mixture was stirred overnightat 70° C. under nitrogen atmosphere, saturated aqueous ammonium chloridesolution was added thereto, and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (11.6g).

MS (API+): [M+H]⁺363.0.

C)N-((4-bromo-2-fluorophenyl)(4-(trifluoromethoxy)phenyl)methyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from(4-bromo-2-fluorophenyl)(4-(trifluoromethoxy)phenyl)methanone in thesame manner as in Step D of Example 2, Step B of Example 132 and Step Bof Example 83.

MS (API+): [M+H]⁺ 553.1.

Example 196N-((4-bromo-2-hydroxyphenyl)(4-(trifluoromethoxy)phenyl)methyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-bromo-2-fluorobenzoic acid in thesame manner as in Step A of Example 31, Step B of Example 195, Step D ofExample 2, Step B of Example 132 and Step B of Example 83.

MS (API+): [M+H]⁺551.1.

Example 197N-(2-((5-bromopyridin-3-yl)oxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained in the same manner as in Step A ofExample 181, Step D of Example 2, Step B of Example 132 and Step G ofExample 7.

MS (API+): [M+H]⁺566.1.

Example 198N-((2-fluorophenyl)(4-(trifluoromethoxy)phenyl)methyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

A mixture ofN-((4-bromo-2-fluorophenyl)(4-(trifluoromethoxy)phenyl)methyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(60 mg), 5% palladium-carbon (containing 50% water, 15 mg) and methanol(5 mL) was stirred for 2 hr under hydrogen atmosphere. The catalyst wasfiltered off, and the filtrate was concentrated under reduced pressureto give the title compound (35.6 mg).

MS (API+): [M+H]⁺475.2.

Example 199N-((2-hydroxyphenyl)(4-(trifluoromethoxy)phenyl)methyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained fromN-((4-bromo-2-hydroxyphenyl)(4-(trifluoromethoxy)phenyl)methyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidein the same manner as in Example 198.

MS (API+): [M+H]⁺473.2.

Example 2007-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

A diastereomeric mixture (110 mg) of7-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidewas resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/2-propanol=70/30) to give the title compound having a shortestretention time (28 mg).

MS (API+): [M+H]⁺451.2.

Example 2017-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

A diastereomeric mixture (110 mg) of7-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidewas resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/2-propanol=70/30) to give the title compound having a secondshortest retention time (16 mg).

MS (API+): [M+H]⁺451.2.

Example 2027-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

A diastereomeric mixture (110 mg) of7-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidewas resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/2-propanol=70/30) to give the title compound having a thirdshortest retention time (33 mg).

MS (API+): [M+H]⁺451.2.

Example 2037-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

A diastereomeric mixture (110 mg) of7-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidewas resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/2-propanol=70/30) to give the title compound having a longestretention time (14 mg).

MS (API+): [M+H]⁺451.2.

Example 2047-methoxy-2-oxo-N-(1-(4-(pyrrolidin-1-yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(4-(1H-pyrrol-1-yl)phenyl)propan-1-amine in the same manner as inSteps I-L of Example 66.

MS (API−): [M−H]⁻408.2.

Example 205N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate

To a solution of 2-chloro-5-iodo-3-nitropyridine (12.0 g) in ethanol(200 mL) were added methyl glycinate hydrochloride (10.6 g) andtriethylamine (11.8 mL) at room temperature. The reaction mixture washeated at reflux for 20 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue wascrystallized from hexane/ethyl acetate to give the title compound (11.1g).

MS (API+): [M+H]⁺338.0.

B) 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl N-(5-iodo-3-nitropyridin-2-yl)glycinate (6.00 g)in tetrahydrofuran (300 mL) was added 5% platinum-carbon (500 mg). Thereaction mixture was stirred overnight at room temperature underhydrogen atmosphere, the catalyst was filtered off, and the filtrate wasconcentrated under reduced pressure. The residue was dissolved inethanol (200 mL), the solution was heated at reflux for 16 hr, and thesolvent was evaporated under reduced pressure. The residue was washedwith diisopropyl ether to give the title compound (4.48 g).

MS (API+): [M+H]⁺276.0.

C)7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a suspension of 7-iodo-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(3.82 g) in N,N-dimethylformamide (160 mL) was slowly added 1 Mpotassium hexamethyldisilazide/tetrahydrofuran solution (17.4 mL) at 0°C. The reaction mixture was stirred at 0° C. for 1 hr,2-(chloromethoxy)ethyltrimethylsilane (3.62 mL) was slowly addedthereto, and the mixture was stirred at room temperature for 20 hr. Tothe reaction mixture was added water, the insoluble substance wasfiltered off using Celite, and the filtrate was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (NH, hexane/ethyl acetate) to give the titlecompound (2.71 g).

MS (API+): [M+H]⁺406.0.

D) methyl2-((tert-butoxycarbonyl)amino)-2-(4-(trifluoromethoxy)phenyl)acetate

To a mixture of 4-trifluoromethoxybenzaldehyde (19.0 g) and ammoniumcarbonate (25.9 g) in a mixed solvent of ethanol (114 mL) and water(45.6 mL) was slowly added an aqueous solution (71.1 mL) of potassiumcyanide (8.14 g) at 50° C. The reaction mixture was stirred at 60° C.for 3 hr, and cooled to room temperature, and the ethanol was evaporatedunder reduced pressure. The pH of the residue was adjusted to 1 withconc. hydrochloric acid at 0° C., and the resulting solid was collectedby filtration, and washed with water. The obtained solid was added to anaqueous solution (100 mL) of potassium hydroxide (23.6 g) at roomtemperature, and the reaction mixture was stirred at 90° C. for 3 days.The reaction mixture was cooled to room temperature, and neutralizedwith conc. hydrochloric acid. The resulting solid was collected byfiltration, and washed with water to give a crude product (13.3 g) of2-amino-2-(4-(trifluoromethoxy)phenyl)acetic acid. To a solution of theobtained crude product (13.3 g) in tetrahydrofuran (113 mL) were addeddi-tert-butyl dicarbonate (19.7 mL) and 2 M aqueous sodium hydroxidesolution (85 mL) at room temperature. The reaction mixture was stirredovernight at room temperature, and poured into water, and the mixturewas washed with diethyl ether. The pH of the aqueous layer was adjustedto 3 with 1 M hydrochloric acid at 0° C., and the mixture was extractedwith ethyl acetate. The extract was washed with saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure to give a crude product (11.3 g) of2-((tert-butoxycarbonyl)amino)-2-(4-(trifluoromethoxy)phenyl)aceticacid. To a solution of the obtained crude product (11.3 g) inN,N-dimethylformamide (84 mL) were added methyl iodide (2.53 mL) andpotassium carbonate (5.59 g) at room temperature. The reaction mixturewas stirred at room temperature for 2 hr, and poured into water, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (8.20 g).

MS (API−): [M−H]⁻348.1.

E)tert-butyl(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate

To a solution of methyl2-((tert-butoxycarbonyl)amino)-2-(4-(trifluoromethoxy)phenyl)acetate(5.00 g) in tetrahydrofuran (71.6 mL) was slowly added 1 Mmethylmagnesium bromide/tetrahydrofuran solution (57.3 mL) at 0° C. Thereaction mixture was stirred at 0° C. for 1 hr under argon atmosphere,saturated aqueous ammonium chloride solution was added thereto at 0° C.,and the mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous magnesium sulfate, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (3.99 g).

MS (API−): [M−H]⁻348.2.

F) 1-amino-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-olhydrochloride

Totert-butyl(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate(2.50 g) was added 4 M hydrogen chloride/ethyl acetate solution (71.6mL). The reaction mixture was stirred at room temperature for 1 hr, andthe solvent was evaporated under reduced pressure. To the residue wasadded diisopropyl ether, and the resulting crystals were collected byfiltration to give the title compound (2.01 g).

MS (API+), found: 250.1.

G)N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-iodo-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-iodo-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(500 mg) in tetrahydrofuran (18.9 mL) was slowly added a solution ofbis(trichloromethyl)carbonate (293 mg) in tetrahydrofuran (2.83 mL) atroom temperature under nitrogen atmosphere. The reaction mixture wasstirred at 40° C. for 3 hr under nitrogen atmosphere, and the solventwas evaporated under reduced pressure. To the residue was addedtetrahydrofuran, and the solvent was evaporated under reduced pressure.The operation (addition of tetrahydrofuran and then evaporation) wasrepeated three times. The residue was diluted with tetrahydrofuran (9.42mL), and the mixture was slowly added to a mixture of1-amino-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-ol hydrochloride(423 mg) and triethylamine (521 μL) in tetrahydrofuran (6.28 mL) at roomtemperature. The reaction mixture was stirred at 60° C. overnight, andthe solvent was evaporated under reduced pressure. To the residue wasadded water, and the mixture was extracted with ethyl acetate. Theextract was washed with saturated brine, and dried over anhydrous sodiumsulfate, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (hexane/ethylacetate) to give the title compound (729 mg).

MS (API+): [M+H]⁺ 681.1.

H)7-hydroxy-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a mixture ofN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-iodo-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(699 mg), 4,4,4′,4′,5,5,5′,5′-octamethyl-2,2′-bi-1,3,2-dioxaborolane(537 mg) and potassium acetate (415 mg) in N,N-dimethylformamide (10.3mL) was added (1,1-bis(diphenylphosphino)ferrocene)dichloropalladium(II)(77.0 mg). The reaction mixture was stirred overnight at 80° C. underargon atmosphere, water was added thereto, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure to give a crude product(986 mg) ofN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-7-(4,4,5,5-tetramethyl-1,3-2-dioxaborolan-2-yl-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide.To a solution of the obtained crude product (986 mg) in tetrahydrofuran(14.5 mL) was added 2 M aqueous sodium hydroxide solution (2.90 mL) at0° C. The reaction mixture was stirred at 0° C. for 30 min, 35% aqueoushydrogen peroxide (508 μL) was added thereto. The reaction mixture wasstirred at room temperature for 2 hr, ice water was added thereto, andthe mixture was acidified with 1 M hydrochloric acid, and extracted withethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (340 mg).

MS (API+): [M+H]⁺571.2.

I)N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of7-hydroxy-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(340 mg) in N,N-dimethylformamide (7.64 mL) were added potassiumcarbonate (83.0 mg) and iodomethane (56.1 μL). The reaction mixture wasstirred overnight at room temperature, water was added thereto, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) and then HPLC(C18, mobile phase: water (10 mM, containing NH₄HCO₃)/acetonitrile), andthe obtained fraction was concentrated under reduced pressure to givethe title compound (91.0 mg).

MS (API+): [M+H]⁺585.3.

J)N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

ToN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(90.9 mg) were added trifluoroacetic acid (2.24 mL) and water (251 μL).The reaction mixture was stirred at room temperature for 1 hr, and thesolvent was evaporated under reduced pressure. The residue was dissolvedin N,N-dimethylformamide (4.27 mL), and 8 M ammonia/methanol solution(838 μL) was added thereto. The reaction mixture was stirred at roomtemperature for 10 min, and the solvent was evaporated under reducedpressure. The residue was diluted with ethyl acetate, and the mixturewas washed successively with water and saturated brine, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. The obtained solid was washed with hexane/ethyl acetate togive the title compound (48.8 mg).

MS (API+): [M+H]⁺455.3.

¹H NMR (300 MHz, DMSO-d₆) δ 0.98 (3H, s), 1.18 (3H, s), 3.84 (3H, s),4.25-4.49 (2H, m), 4.67 (1H, d, J=8.3 Hz), 4.77 (1H, s), 6.96 (1H, d,J=2.6 Hz), 7.27 (2H, d, J=7.9 Hz), 7.42 (2H, d, J=8.7 Hz), 7.76 (1H, d,J=2.6 Hz), 10.19 (1H, d, J=8.3 Hz), 10.73 (1H, brs).

Example 2067-methyl-2-oxo-N-(tetrahydrofuran-3-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from tetrahydrofuran-3-carboxylic acidin the same manner as in Step A of Example 170, Step D of Example 2,Step B of Example 132 and Step G of Example 7.

MS (API+): [M+H]⁺451.2.

Example 207N-((1S)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(43.8 mg) was resolved by SFC (column: CHIRALPAK ADH, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=800/200), and crystallized from hexane/ethyl acetate togive the title compound having a shorter retention time (5.4 mg).

MS (API+): [M+H]⁺455.2.

¹H NMR (300 MHz, DMSO-d₆) δ 0.98 (3H, s), 1.18 (3H, s), 3.84 (3H, s),4.20-4.50 (2H, m), 4.67 (1H, d, J=8.3 Hz), 4.77 (1H, s), 6.96 (1H, d,J=3.0 Hz), 7.27 (2H, d, J=7.9 Hz), 7.42 (2H, d, J=8.7 Hz), 7.76 (1H, d,J=2.6 Hz), 10.19 (1H, d, J=8.3 Hz), 10.73 (1H, brs).

Example 208N-((1R)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(43.8 mg) was resolved by SFC (column: CHIRALPAK ADH, 20 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase: carbondioxide/methanol=800/200), and crystallized from hexane/ethyl acetate togive the title compound having a longer retention time (5.2 mg).

MS (API+): [M+H]⁺455.1.

Example 2097-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethanone

The title compound was obtained from2-bromo-1-(3-fluoro-4-(trifluoromethyl)phenyl)ethanone in the samemanner as in Step D of Example 63.

MS (API−): [M−H]⁻235.0.

B) 1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethanaminehydrochloride

The title compound was obtained from1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethanone in the samemanner as in Step E of Example 63.

MS (API+), found: 238.1.

C)N-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-7-iodo-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethanamine hydrochloridein the same manner as in Step F of Example 63.

MS (API+): [M+H]⁺669.1.

D)7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained fromN-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-7-iodo-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidein the same manner as in Step H of Example 72-II.

MS (API+): [M+H]⁺583.2.

E)7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidein the same manner as in Step I of Example 72-II.

MS (API+): [M+H]⁺453.1.

Example 2107-methyl-2-oxo-N-(3,3,3-trifluoro-2-hydroxy-1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) (4-(trifluoromethoxy)phenyl) acetaldehyde

To a mixture of 2-(4-(trifluoromethoxy)phenyl)ethanol (2.00 g) andsodium hydrogen carbonate (8.15 g) in acetonitrile (150 mL) was addedDess-Martin periodinane (8.23 g) at 0° C. The reaction mixture wasstirred at 0° C. for 1 hr, saturated brine was added thereto, and themixture was extracted with ethyl acetate. The extract was washedsuccessively with saturated aqueous sodium hydrogen carbonate solutionand saturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (ethyl acetate) to give the titlecompound (1.72 g).

¹H NMR (300 MHz, CDCl₃) δ 3.72 (2H, d, J=1.9 Hz), 6.84-7.39 (4H, m),9.77 (1H, t, J=2.1 Hz).

B) 1,1,1-trifluoro-3-(4-(trifluoromethoxy)phenyl)propan-2-ol

To a mixture of (4-(trifluoromethoxy)phenyl)acetaldehyde (800 mg) andtrimethyl(trifluoromethyl)silane (2.79 g) in tetrahydrofuran (10 mL) wasadded 1 M tetra-n-butylammonium fluoride/tetrahydrofuran solution (7.84mL) at 0° C. The reaction mixture was stirred at 0° C. for 2 hr, 1 Mhydrochloric acid was added thereto, and the mixture was extracted withethyl acetate. The extract was washed with saturated brine, and driedover anhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (761mg).

¹H NMR (300 MHz, CDCl₃) δ 2.13 (1H, d, J=5.7 Hz), 2.80-2.94 (1H, m),2.97-3.11 (1H, m), 4.01-4.31 (1H, m), 7.04-7.24 (2H, m), 7.27-7.36 (2H,m).

C)tert-butyl(dimethyl)((1,1,1-trifluoro-3-(4-(trifluoromethoxy)phenyl)propan-2-yl)oxy)silane

A mixture of 1,1,1-trifluoro-3-(4-(trifluoromethoxy)phenyl)propan-2-ol(750 mg), tert-butyldimethylsilyl trifluoromethanesulfonate (1.09 g),2,6-dimethylpyridine (586 mg) and tetrahydrofuran (5 mL) was stirred at0° C. for 2 hr. The reaction mixture was added to saturated aqueoussodium hydrogen carbonate solution, and the mixture was extracted withethyl acetate. The extract was washed successively with 1 M hydrochloricacid and saturated aqueous sodium hydrogen carbonate solution, and driedover anhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (434mg).

¹H NMR (300 MHz, CDCl₃) δ −0.48 (3H, s), −0.05 (3H, s), 0.72-0.79 (9H,m), 2.80 (1H, dd, J=13.8, 10.0 Hz), 3.03 (1H, dd, J=13.8, 2.8 Hz),3.93-4.25 (1H, m), 7.07-7.20 (2H m), 7.21-7.25 (2H, m).

D)((3-bromo-1,1,1-trifluoro-3-(4-(trifluoromethoxy)phenyl)propan-2-yl)oxy)(tert-butyl)dimethylsilane

A mixture oftert-butyl(dimethyl)((1,1,1-trifluoro-3-(4-(trifluoromethoxy)phenyl)propan-2-yl)oxy)silane(165 mg), 2,2′-(diazene1,2-diyl)bis(2-methylpropanenitrile) (6.98 mg),1-bromopyrrolidine-2,5-dione (98 mg) and benzotrifluoride (5 mL) wasstirred overnight at 130° C., were added 1-bromopyrrolidine-2,5-dione(227 mg) and 2,2′-(diazene-1,2-diyl)bis(2-methylpropanenitrile) (14.0mg), and the reaction mixture was stirred at 130° C. for 6 hr.Separately, a mixture oftert-butyl(dimethyl)((1,1,1-trifluoro-3-(4-(trifluoromethoxy)phenyl)propan-2-yl)oxy)silane(200 mg), 2,2′-(diazene-1,2-diyl)bis(2-methylpropanenitrile) (42.3 mg),1-bromopyrrolidine-2,5-dione (458 mg) and benzotrifluoride (10 mL) wasstirred at 120° C. for 2 days. These mixtures were combined, hexane wasadded thereto, and the insoluble substance was filtered off. Thefiltrate was concentrated under reduced pressure, and the residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive a pale yellow oil (385 mg). To a solution of this oil (380 mg) inN,N-dimethylformamide (15 mL) was added sodium azide (264 mg) at roomtemperature. The reaction mixture was stirred overnight at 100° C.,saturated brine was added thereto, and the mixture was extracted withethyl acetate. The extract was washed with saturated brine, and driedover anhydrous magnesium sulfate to give an orange oil (280 mg). To asolution of this oil (280 mg) in methanol (5 mL) was added 10%palladium-carbon (containing 50% water, 20 mg). The reaction mixture wasstirred overnight under hydrogen atmosphere, the catalyst was filteredoff, and the filtrate was concentrated under reduced pressure. To theresidue were added triethylamine (92 mg),4-nitrophenyl-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate(100 mg) and N,N-dimethylformamide (5 mL). The reaction mixture wasstirred overnight at room temperature, saturated aqueous sodium hydrogencarbonate solution was added thereto, and the mixture was extracted withethyl acetate. The extract was washed successively with saturatedaqueous sodium hydrogen carbonate solution and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by HPLC (C18, mobilephase: water/acetonitrile (containing 0.1% TFA)), to the obtainedfraction was added saturated aqueous sodium hydrogen carbonate solution,and the mixture was extracted with ethyl acetate. The extract was driedover anhydrous magnesium sulfate, and concentrated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate) to give the title compound (23.2 mg).

MS (API+): [M+H]⁺479.1.

Example 211N-(1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA)N-(1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethanamine in the samemanner as in Steps I-K of Example 66.

MS (API+): [M+H]⁺570.3.

B)N-(1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution ofN-(1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(112 mg) in dichloromethane (3.72 mL) was added boron trifluoridediethyl ether complex (250 μL) at 0° C. The reaction mixture was stirredat 0° C. for 1 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith diethyl ether. The extract was washed with saturated brine, anddried over anhydrous sodium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was dissolved in methanol (5.00 mL),N-ethyl-N-isopropylpropan-2-amine (344 L) was added thereto at roomtemperature. The reaction mixture was stirred at 50° C. for 1 hr, thesolvent was evaporated under reduced pressure, and the obtained solidwas washed with hexane/ethyl acetate to give the title compound (58.8mg).

MS (API+): [M+H]⁺440.2.

Example 2126-(4-methoxyphenyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl 2-((6-chloro-3-nitropyridin-2-yl)amino)acetate

The title compound was obtained from 2,6-dichloro-3-nitropyridine in thesame manner as in Step A of Example 1.

¹H NMR (300 MHz, DMSO-d₆) δ 3.67 (3H, s), 4.27 (2H, d, J=6.0 Hz), 6.87(1H, d, J=8.7 Hz), 8.48 (1H, d, J=8.7 Hz), 8.96 (1H, t, J=5.7 Hz).

B) 6-chloro-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

The title compound was obtained from methyl2-((6-chloro-3-nitropyridin-2-yl)amino)acetate in the same manner as inStep B of Example 66.

¹H NMR (300 MHz, DMSO-d₆) δ 3.94 (2H, s), 6.55 (1H, d, J=7.9 Hz), 6.91(1H, d, J=7.9 Hz), 7.19 (1H, s), 10.47 (1H, s).

C)6-chloro-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

The title compound was obtained from6-chloro-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one in the same manner asin Step C of Example 63.

MS (API+): [M+H]⁺314.3.

D)6-chloro-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from6-chloro-1-((2-(trimethylsilyl)ethoxy)methyl)-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-onein the same manner as in Step F of Example 63.

MS (API+): [M+H]⁺575.2.

E)6-(4-methoxyphenyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of6-chloro-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(69.0 mg) in 1,2-dimethoxyethane (1.5 mL) were added4-methoxyphenylboronic acid (36.5 mg), 1 M potassium carbonate aqueoussolution (0.24 mL) andbis(di-tert-butyl(4-dimethylaminophenyl)phosphine)dichloropalladium(II)(8.5 mg), and the mixture was heated at 120° C. for 1 hr using microwavegenerator (Biotage, Initiator Sixty). To a reaction solution were addedwater (1 mL) and ethyl acetate (2 mL), and the mixture was stirred, andfiltered through phase separating filter, and the organic layer wasconcentrated using air spraying device. The residue was purified by HPLC(column: YMC Triart C18, mobile phase: acetonitrile/10 mM aqueousammonium bicarbonate solution), and the solvent was evaporated using airspraying device. To the residue was added trifluoroacetic acid (1 mL),and the mixture was stirred at room temperature for 1 hr, and thesolvent was evaporated using air spraying device. To the residue wasadded 8 M ammonia/methanol solution (1 mL), the mixture was stirred atroom temperature for 1 hr, and the solvent was evaporated using airspraying device. The residue was purified by HPLC (column: YMC TriartC18, mobile phase: acetonitrile/10 mM aqueous ammonium bicarbonatesolution), and the solvent was evaporated using air spraying device togive the title compound (36.7 mg).

MS (API+): [M+H]⁺517.1.

Example 213N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(pyridin-3-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from pyridin-3-ylboronic acid in thesame manner as in Step E of Example 212.

MS (API+): [M+H]⁺488.1.

Example 214N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-phenyl-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from phenylboronic acid in the samemanner as in Step E of Example 212.

MS (API+): [M+H]⁺487.1.

Example 2156-(2-methoxyphenyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 2-methoxyphenylboronic acid in thesame manner as in Step E of Example 212.

MS (API+): [M+H]⁺517.1.

Example 2166-(3-methoxyphenyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 3-methoxyphenylboronic acid in thesame manner as in Step E of Example 212.

MS (API+): [M+H]⁺517.2.

Example 217N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(pyridin-4-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from pyridin-4-ylboronic acid in thesame manner as in Step E of Example 212.

MS (API+): [M+H]⁺488.1.

Example 218N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(2-thienyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 2-thienylboronic acid in the samemanner as in Step E of Example 212.

MS (API+): [M+H]⁺493.1.

Example 2196-(3-furyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 3-furylboronic acid in the samemanner as in Step E of Example 212.

MS (API+): [M+H]⁺477.1.

Example 220N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(3-thienyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 3-thienylboronic acid in the samemanner as in Step E of Example 212.

MS (API+): [M+H]⁺493.1.

Example 221N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-(1-methyl-1H-pyrazol-5-yl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-methyl-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole inthe same manner as in Step E of Example 212.

MS (API+): [M+H]⁺491.1.

Example 222N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-(1-methyl-1H-pyrazol-3-yl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole inthe same manner as in Step E of Example 212.

MS (API+): [M+H]⁺491.1.

Example 223N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-(1-methyl-1H-pyrazol-4-yl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-methyl-4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-1H-pyrazole inthe same manner as in Step E of Example 212.

MS (API+): [M+H]⁺491.1.

Example 2246-(3,5-dimethyl-1,2-oxazol-4-yl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 3,5-dimethyl-1,2-oxazol-4-ylboronicacid in the same manner as in Step E of Example 212.

MS (API+): [M+H]⁺506.1.

Example 225N-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained fromN-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-7-iodo-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidein the same manner as in Steps J-L of Example 66.

MS (API+): [M+H]⁺443.1.

Example 226 Optically active7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(347 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=700/300) to give the title compound having a shorterretention time (107 mg).

MS (API+): [M+H]⁺453.1.

Example 227 Optically active7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(347 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=700/300) to give the title compound having a longerretention time (83 mg).

MS (API+): [M+H]⁺453.1.

Example 228N-(2-methoxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl 2-(4-(trifluoromethoxy)phenyl)acetate

To a solution of 2-(4-(trifluoromethoxy)phenyl)acetic acid (5.00 g) inmethanol (32 mL) was added conc. sulfuric acid (0.237 mL) at roomtemperature. The reaction mixture was stirred at 70° C. for 4 hr, andconcentrated to about 10 mL under reduced pressure. To the residue wasadded water, and the mixture was extracted with ethyl acetate. Theextract was washed with saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reduced pressureto give the title compound (4.00 g).

MS (API−): [M−H]⁻ 233.0.

B) 2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-ol

To a solution of methyl 2-(4-(trifluoromethoxy)phenyl)acetate (4.00 g)in tetrahydrofuran (57 mL) was added 1 M methylmagnesiumbromide/tetrahydrofuran solution (42.7 mL) at 0° C. The reaction mixturewas stirred at room temperature for 4 hr, saturated aqueous ammoniumchloride solution was added thereto at 0° C., and the mixture wasextracted with ethyl acetate. The extract was washed with saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (hexane/ethyl acetate) to give the titlecompound (3.26 g).

¹H NMR (300 MHz, DMSO-d₆) δ 1.06 (6H, s), 2.67 (2H, s), 4.36 (1H, s),7.31 (4H, s).

C) 1-(2-methoxy-2-methylpropyl)-4-(trifluoromethoxy)benzene

To a solution of 2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-ol(6.72 g) in N,N-dimethylformamide (140 mL) was added 60% sodium hydride(5.74 g) at room temperature. The reaction mixture was stirred at roomtemperature for 30 min, methyl iodide (8.97 mL) was slowly added theretoat room temperature, and the mixture was stirred at room temperature for18 hr. To the reaction mixture was added water, and the mixture wasextracted with ethyl acetate. The extract was dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate) to give the title compound (6.01 g).

¹H NMR (300 MHz, DMSO-d₆) δ 1.05 (6H, s), 2.75 (2H, s), 3.16 (3H, s),7.17-7.37 (4H, m).

D) 1-(1-bromo-2-methoxy-2-methylpropyl)-4-(trifluoromethoxy)benzene

The title compound was obtained from1-(2-methoxy-2-methylpropyl)-4-(trifluoromethoxy)benzene in the samemanner as in Step D of Example 142.

¹H NMR (300 MHz, DMSO-d) δ 1.13 (3H, s), 1.25 (3H, s), 3.20 (3H, s),5.33-5.42 (1H, m), 7.18-7.38 (2H, m), 7.62-7.70 (2H, m).

E) 1-(1-azido-2-methoxy-2-methylpropyl)-4-(trifluoromethoxy)benzene

To a solution of1-(1-bromo-2-methoxy-2-methylpropyl)-4-(trifluoromethoxy)benzene (2.10g) in N,N-dimethylformamide (43 mL) were added sodium azide (2.09 g) and18-crown-6 (6.8 g). The reaction mixture was stirred at 100° C. for 18hr, water was added thereto, and the mixture was extracted with diethylether. The extract was washed with saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure to give the title compound (1.66 g).

¹H NMR (300 MHz, DMSO-d₆) δ 1.00-1.11 (6H, m), 3.20 (3H, s), 4.83-4.90(1H, m), 7.33-7.40 (2H, m), 7.42-7.56 (2H, m).

F)N-(2-methoxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(1-azido-2-methoxy-2-methylpropyl)-4-(trifluoromethoxy)benzene in thesame manner as in Steps E-F of Example 2 and Step L of Example 72-I.

MS (API+): [M+H]⁺ 453.2.

Example 229 Optically activeN-(1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(55.2 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=700/300) to give the title compound having a shorterretention time (13.7 mg).

MS (API+): [M+H]⁺440.2.

Example 230 Optically activeN-(1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(55.2 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=700/300) to give the title compound having a longerretention time (15.4 mg).

MS (API+): [M+H]⁺440.2.

Example 231 Optically active7-cyclopropyl-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-cyclopropyl-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(426 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=700/300) to give the title compound having a shorterretention time (177 mg).

MS (API+): [M+H]⁺435.1.

¹H NMR (300 MHz, CDCl₃) δ 0.66-0.75 (2H, m), 0.98-1.08 (2H, m),1.83-1.95 (1H, m), 3.40 (3H, s), 3.69 (2H, d, J=5.3 Hz), 4.64 (2H, s),5.16-5.26 (1H, m), 6.83 (1H, d, J=2.3 Hz), 7.45-7.62 (4H, m), 7.84 (1H,d, J=1.9 Hz), 8.84-8.97 (1H, m), 10.55 (1H, d, J=7.2 Hz).

Example 232 Optically activeN-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(471 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=700/300), and recrystallized from hexane/ethyl acetate togive the title compound having a shorter retention time (208 mg).

MS (API+): [M+H]⁺443.1.

Example 233 Optically active7-cyclopropyl-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-cyclopropyl-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(426 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=700/300), and recrystallized from hexane/ethyl acetate togive the title compound having a longer retention time (179 mg).

MS (API+): [M+H]⁺435.1.

¹H NMR (300 MHz, CDCl₃) δ 0.66-0.75 (2H, m), 0.98-1.08 (2H, m),1.81-1.94 (1H, m), 3.40 (3H, s), 3.69 (2H, d, J=5.3 Hz), 4.64 (2H, s),5.14-5.26 (1H, m), 6.83 (1H, d, J=1.9 Hz), 7.45-7.64 (4H, m), 7.84 (1H,d, J=1.9 Hz), 9.01 (1H, s), 10.55 (1H, d, J=7.2 Hz).

Example 234 Optically activeN-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(471 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=700/300) to give the title compound having a longerretention time (199 mg).

MS (API+): [M+H]⁺443.1.

Example 2356-(3,6-dihydro-2H-pyran-4-yl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 3,6-dihydro-2H-pyran-4-boronic acidpinacol ester in the same manner as in Step E of Example 212.

MS (API+): [M+H]⁺493.1.

Example 236N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-methyl-1,2,3,6-tetrahydropyridine-4-boronic acid pinacol ester in thesame manner as in Step E of Example 212.

MS (API+): [M+H]⁺506.1.

Example 237N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(1,2,3,6-tetrahydropyridin-4-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from tert-butyl4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-5,6-dihydropyridine-1(2H)-carboxylatein the same manner as in Step E of Example 212.

MS (API+): [M+H]⁺492.1.

Example 238N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of6-chloro-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(46.0 mg) in 1,2-dimethoxyethane (1.0 mL) was added water (0.16 mL),trimethylboroxine (50.0 mg), cesium carbonate (52.0 mg) andbis(di-tert-butyl(4-dimethylaminophenyl)phosphine)dichloropalladium(II)(5.6 mg), and the mixture was heated at 110° C. for 1 hr using microwavegenerator (Biotage, Initiator Sixty). To the reaction mixture were addedwater (1 mL) and ethyl acetate (2 mL), and the mixture was stirred, andfiltered through phase separating filter, and the organic layer wasconcentrated using air spraying device. The residue was purified by HPLC(column: YMC Triart C18, mobile phase: acetonitrile/10 mM aqueousammonium bicarbonate solution), and the solvent was evaporated using airspraying device. To the residue was added trifluoroacetic acid (1 mL),and the mixture was stirred at room temperature for 1 hr, and thesolvent was evaporated using air spraying device. To the residue wasadded 8 M ammonia/methanol solution (1 mL), and the mixture was stirredat room temperature for 1 hr, and the solvent was evaporated using airspraying device. The residue was purified by HPLC (column: YMC TriartC18, mobile phase: acetonitrile/10 mM aqueous ammonium bicarbonatesolution), and the solvent was evaporated using air spraying device togive the title compound (16.5 mg).

MS (API+): [M+H]⁺425.0.

Example 239N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(pyridin-2-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of6-chloro-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide (46.0mg) in N,N-dimethylformamide (0.5 mL) were added (2-pyridine)cyclictriolborate lithium (51.1 mg), cesium carbonate (78.1 mg),bis(di-tert-butyl(4-dimethylaminophenyl)phosphine)dichloropalladium(II)(5.6 mg) and copper(I) chloride (4.0 mg), and the mixture was heated at100° C. for 1 hr using microwave generator (Biotage, Initiator Sixty).To the reaction mixture were added water (1 mL) and ethyl acetate (2mL), and the mixture was stirred, and filtered through phase separatingfilter, and the organic layer was concentrated using air sprayingdevice. The residue was purified by HPLC (column: YMC Triart C18, mobilephase: acetonitrile/10 mM aqueous ammonium bicarbonate solution), andthe solvent was evaporated using air spraying device. To the residue wasadded trifluoroacetic acid (1 mL), and the mixture was stirred at roomtemperature for 1 hr, and the solvent was evaporated using air sprayingdevice. To the residue was added 8 M ammonia/methanol solution (1 mL),and the mixture was stirred at room temperature for 1 hr, and thesolvent was evaporated using air spraying device. The residue waspurified by HPLC (column: YMC Triart C18, mobile phase: acetonitrile/10mM aqueous ammonium bicarbonate solution), and the solvent wasevaporated using air spraying device to give the title compound (6.3mg).

MS (API+): [M+H]⁺488.1.

Example 2406-(2-furyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from sodium (2-furan)cyclic-triolboratein the same manner as in Example 239.

MS (API+): [M+H]⁺477.1.

Example 2416-cyclopropyl-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of6-chloro-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-1-((2-(trimethylsilyl)ethoxy)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(46.0 mg) in toluene (1.0 mL) were added water (0.2 mL),cyclopropylboronic acid (20.6 mg), cesium carbonate (78.1 mg),palladium(II) acetate (3.6 mg) and tricyclohexylphosphine (6.7 mg), andthe mixture was heated at 100° C. for 30 min using microwave generator(Biotage, Initiator Sixty). To the reaction mixture were added water (1mL) and ethyl acetate (2 mL), and the mixture was stirred, and filteredthrough phase separating filter, and the organic layer was concentratedusing air spraying device. The residue was purified by HPLC (column: YMCTriart C18, mobile phase: acetonitrile/10 mM aqueous ammoniumbicarbonate solution), and the solvent was evaporated using air sprayingdevice. To the residue was added trifluoroacetic acid (1 mL), and themixture was stirred at room temperature for 1 hr, and the solvent wasevaporated using air spraying device. To the residue was added 8 Mammonia/methanol solution (1 mL), and the mixture was stirred at roomtemperature for 1 hr, and the solvent was evaporated using air sprayingdevice. The residue was purified by HPLC (column: YMC Triart C18, mobilephase: acetonitrile/10 mM aqueous ammonium bicarbonate solution), andthe solvent was evaporated using air spraying device to give the titlecompound (18.3 mg).

MS (API+): [M+H]⁺451.1.

Example 242N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(tetrahydro-2H-pyran-4-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of6-(3,6-dihydro-2H-pyran-4-yl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(10 mg) in methanol (2 mL) were added ammonium formate (50 mg) and 5%palladium-carbon-ethylene diamine complex (50 mg), and the mixture wasstirred at 60° C. for 2 hr. The reaction mixture was filtered, andconcentrated using air spraying device. The residue was purified by HPLC(column: YMC Triart C18, mobile phase: acetonitrile/10 mM aqueousammonium bicarbonate solution), and the solvent was evaporated using airspraying device to give the title compound (5.5 mg).

MS (API+): [M+H]⁺495.1.

Example 243N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-(1-methylpiperidine-4-yl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained fromN-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidein the same manner as in Example 242.

MS (API+): [M+H]⁺508.1.

Example 244N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(piperidin-4-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained fromN-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(1,2,3,6-tetrahydropyridin-4-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamidein the same manner as in Example 242.

MS (API+): [M+H]⁺494.1.

Example 2456-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-chloro-3-methyl-5-nitropyridine 1-oxide

To a mixture of 2-chloro-3-methyl-5-nitropyridine (5.00 g) and hydrogenperoxide urea (5.72 g) in acetonitrile (37.6 mL) was slowly addedtrifluoroacetic anhydride (8.06 mL) at 0° C. The reaction mixture wasstirred at 0° C. for 2 hr, 9% (w/w) aqueous sodium dithionite solution(60 mL) was added thereto, and the mixture was stirred at roomtemperature for 20 min. The reaction mixture was extracted with ethylacetate. The extract was washed successively with saturated aqueoussodium hydrogen carbonate solution and saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (1.90g).

¹H NMR (300 MHz, DMSO-d₆) δ 2.33 (3H, s), 7.98 (1H, d, J=0.8 Hz), 8.70(1H, dd, J=1.7, 0.8 Hz).

B) 2,6-dichloro-3-methyl-5-nitropyridine

A mixture of 2-chloro-3-methyl-5-nitropyridine 1-oxide (8.17 g) andphosphorus oxychloride (101 mL) was stirred at 90° C. for 30 min, andthe solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (7.63 g).

¹H NMR (300 MHz, CDCl₃) δ 2.48 (3H, s), 8.14 (1H, d, J=0.8 Hz).

C) methyl 2-(6-chloro-5-methyl-3-nitropyridin-2-yl)acetate

The title compound was obtained from2,6-dichloro-3-methyl-5-nitropyridine in the same manner as in Step A ofExample 1.

MS (API+): [M+H]⁺260.0.

D) methyl 2-(6-methoxy-5-methyl-3-nitropyridin-2-yl)acetate

A mixture of methyl 2-(6-chloro-5-methyl-3-nitropyridin-2-yl)acetate(2.63 g) and sodium methoxide (2.93 g) in methanol (50.6 mL) was stirredovernight at room temperature, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (1.12g).

MS (API+): [M+H]⁺256.1.

E)6-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from methyl2-(6-methoxy-5-methyl-3-nitropyridin-2-yl)acetate in the same manner asin Step B of Example 1 and Steps C-D of Example 19.

MS (API+): [M+H]⁺455.1.

Example 2467-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 2-nitroacetamide ammonia salt

A mixture of 2-nitroethyl acetate (17.5 g) and 28% aqueous ammoniasolution (88 mL) was stirred at room temperature for 4 days, and thesolvent was evaporated under reduced pressure to give the title compound(15.0 g).

¹H NMR (300 MHz, D₂O) δ 6.43 (2H, s)

B) methyl 2-((5-methoxy-6-methyl-3-nitropyridin-2-yl)amino)acetate

To a solution of 28% sodium methoxide/methanol solution (16.7 g) inmethanol (87 mL) was slowly added a mixture of 1-methoxypropan-2-one(7.63 g) and ethyl formate (7.68 mL) at −10° C. The reaction mixture wasstirred at −10° C. for 1 hr under argon atmosphere, and then overnightat room temperature, and the solvent was evaporated under reducedpressure. To a solution of the residue (12.0 g) and 2-nitroacetamideammonia salt (12.9 g) in water (54.1 mL) were added 3.4 M aqueouspiperidine acetate solution (26.7 mL) and acetic acid (5.85 mL) at roomtemperature. The reaction mixture was stirred overnight at 50° C., waterwas added thereto, and the mixture was extracted with ethyl acetate. Theextract was washed with saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate) to give 5-methoxy-6-methyl-3-nitropyridin-2-ol(1.06 g) containing an impurity. To a solution of the5-methoxy-6-methyl-3-nitropyridin-2-ol obtained above (153 mg) inpyridine (4.15 mL) was added trifluoromethanesulfonic anhydride (211 μL)at 0° C. The reaction mixture was stirred at 0° C. for 2 hr, water wasadded thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with 1 M hydrochloric acid, saturatedaqueous sodium hydrogen carbonate solution and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. To a solution of the residue (262 mg) inN,N-dimethylacetamide (4.15 mL) were added glycinemethyl esterhydrochloride (125 mg) and triethylamine (289 μL) at room temperature.The reaction mixture was stirred overnight at 70° C., water was addedthereto, and the mixture was extracted with ethyl acetate. The extractwas washed with saturated brine, and dried over anhydrous magnesiumsulfate, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (hexane/ethylacetate) to give the title compound (70 mg).

MS (API+): [M+H]⁺256.1.

C)7-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from methyl2-((5-methoxy-6-methyl-3-nitropyridin-2-yl)amino)acetate in the samemanner as in Step B of Example 1 and Steps C-D of Example 19.

MS (API+): [M+H]⁺455.1.

Example 247N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-nitrophenyl7-methoxy-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylateand 1-amino-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-olhydrochloride in the same manner as in Step C of Example 19.

MS (API+): [M+H]⁺469.1.

Example 248N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-6-methoxy-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-nitrophenyl6-methoxy-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylateand 1-amino-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-olhydrochloride in the same manner as in Step C of Example 19.

MS (API+): [M+H]⁺469.1.

Example 249N-(3-methoxy-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-(3-methoxy-1-(4-(trifluoromethoxy)phenyl))propylamine hydrochloride inthe same manner as in Step C of Example 19.

MS (API+): [M+H]⁺439.1.

Example 250N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl 2-((5-methyl-3-nitropyridin-2-yl)amino)acetate

To a mixture of methyl glycinate hydrochloride (8.32 g) and2-chloro-5-methyl-3-nitropyridine (7.62 g) in N,N-dimethylformamide (100mL) was added triethylamine (18.5 mL). The reaction mixture was stirredat 80° C. for 16 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed with water, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(ethyl acetate/hexane) to give the title compound (6.99 g).

¹H NMR (300 MHz, DMSO-d₆) δ 2.24 (3H, s), 3.64 (3H, s), 4.28 (2H, d,J=5.7 Hz), 8.27-8.37 (2H, m), 8.60 (1H, t, J=5.7 Hz).

B) 7-methyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl 2-((5-methyl-3-nitropyridin-2-yl)amino)acetate(6.99 g) in ethanol (100 mL) was added 10% palladium-carbon (containing50% water, 2.00 g). The reaction mixture was stirred overnight at roomtemperature under hydrogen atmosphere, the catalyst was filtered off,and the filtrate was concentrated under reduced pressure. To the residuewas added ethanol (100 mL), the reaction mixture was heated at refluxfor 5 hr, and the solvent was evaporated to about ⅓ of the volume underreduced pressure. To the residue was added diisopropyl ether, and theprecipitated solid was collected by filtration. The solid was washedwith diisopropyl ether, and dried under reduced pressure to give thetitle compound (4.56 g).

¹H NMR (300 MHz, DMSO-d₆) δ 2.09 (3H, s), 3.85 (2H, d, J=1.5 Hz), 6.45(1H, s), 6.72-6.80 (1H, m), 7.39-7.48 (1H, m), 10.31 (1H, s).

C) 4-nitrophenyl7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate

To a mixture of 7-methyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one (1.00g) in a mixed solvent of N,N-dimethylacetamide (40 mL) and pyridine (15mL) was added 4-nitrophenyl chloroformate (1.48 g) at room temperature.The reaction mixture was stirred at room temperature for 16 hr, andwater was added thereto. The precipitated solid was collected byfiltration, washed with water, and dried under reduced pressure to givethe title compound (1.63 g).

MS (API+): [M+H]⁺ 329.1.

D) methyl2-((tert-butoxycarbonyl)amino)-2-(4-(trifluoromethoxy)phenyl)acetate

To a mixture of 4-trifluoromethoxybenzaldehyde (19.0 g) and ammoniumcarbonate (25.9 g) in a mixed solvent of ethanol (114 mL) and water(45.6 mL) was slowly added an aqueous solution (71.1 mL) of potassiumcyanide (8.14 g) at 50° C. The reaction mixture was stirred at 60° C.for 3 hr, and cooled to room temperature, and the ethanol was evaporatedunder reduced pressure. The pH of the residue was adjusted to 1 withconc. hydrochloric acid at 0° C., and the resulting solid was collectedby filtration, and washed with water. To an aqueous solution (100 mL) ofpotassium hydroxide (23.6 g) was added the solid obtained above at roomtemperature, and the reaction mixture was stirred at 90° C. for 2 days.The reaction mixture was cooled to room temperature, and neutralizedwith conc. hydrochloric acid. The resulting solid was collected byfiltration, and washed with water to give a crude product (13.3 g) of2-amino-2-(4-(trifluoromethoxy)phenyl)acetic acid. To a solution of theobtained crude product (13.3 g) in tetrahydrofuran (113 mL) were addeddi-tert-butyl dicarbonate (19.7 mL) and 2 M aqueous sodium hydroxidesolution (85 mL) at room temperature. The reaction mixture was stirredovernight at room temperature, and poured into water, and the mixturewas washed with diethyl ether. The pH of the aqueous layer was adjustedto 3 with 1 M hydrochloric acid at 0° C., and the mixture was extractedwith ethyl acetate. The extract was washed with saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure to give a crude product (11.3 g) of2-((tert-butoxycarbonyl)amino)-2-(4-(trifluoromethoxy)phenyl)aceticacid. To a solution of the obtained crude product (11.3 g) inN,N-dimethylformamide (84 mL) were added methyl iodide (2.53 mL) andpotassium carbonate (5.59 g) at room temperature. The reaction mixturewas stirred at room temperature for 2 hr, and poured into water, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (8.20 g).

MS (API−): [M−H]⁻348.1.

E)tert-butyl(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate

To a solution of methyl2-((tert-butoxycarbonyl)amino)-2-(4-(trifluoromethoxy)phenyl)acetate(5.00 g) in tetrahydrofuran (71.6 mL) was slowly added 1 Mmethylmagnesium bromide/tetrahydrofuran solution (57.3 mL) at 0° C.under argon atmosphere. The reaction mixture was stirred at 0° C. for 1hr under argon atmosphere, saturated aqueous ammonium chloride solutionwas added thereto at 0° C., and the mixture was extracted with ethylacetate. The extract was washed with saturated brine, and dried overanhydrous magnesium sulfate, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (3.99g).

MS (API−): [M−H]⁻348.2.

F) 1-amino-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-olhydrochloride

Totert-butyl(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)carbamate(2.50 g) was added 4 M hydrogen chloride/ethyl acetate solution (71.6mL). The reaction mixture was stirred at room temperature for 1 hr, andthe solvent was evaporated under reduced pressure. To the residue wasadded diisopropyl ether, and the resulting crystals were collected byfiltration to give the title compound (2.01 g).

MS (API+), found: 250.1.

G)N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a suspension of 4-nitrophenyl7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (263mg) in N,N-dimethylformamide (4.00 mL) were added1-amino-2-methyl-1-(4-(trifluoromethoxy)phenyl)propan-2-ol hydrochloride(251 mg) and triethylamine (245 μL) at room temperature. The reactionmixture was stirred overnight at room temperature, and poured intowater, and the mixture was extracted with ethyl acetate. The extract waswashed with saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate), andthe obtained solid was washed with diisopropyl ether to give the titlecompound (298 mg).

MS (API+): [M+H]⁺439.1.

¹H NMR (300 MHz, DMSO-d₆) δ 0.94-1.03 (3H, m), 1.18 (3H, s), 2.27 (3H,s), 4.27-4.36 (1H, m), 4.37-4.47 (1H, m), 4.68 (1H, d, J=8.3 Hz), 4.78(1H, s), 7.13 (1H, d, J=1.5 Hz), 7.27 (2H, d, J=7.9 Hz), 7.42 (2H, d,J=8.7 Hz), 7.87 (1H, d, J=1.1 Hz), 10.54 (1H, d, J=8.3 Hz), 10.77 (1H,brs).

Example 2517-methoxy-N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(80 mg) was resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=70/30, subsequently changed to 50/50) to give the titlecompound having a shorter retention time (23 mg).

MS (API+): [M+H]⁺455.1.

Example 2527-methoxy-N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(80 mg) was resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=70/30, subsequently changed to 50/50) to give the titlecompound having a longer retention time (18 mg).

MS (API+): [M+H]⁺455.1.

Example 253N-((1S)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(33 mg) was resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=70/30, subsequently changed to 50/50) to give the titlecompound having a shorter retention time (15 mg).

MS (API+): [M+H]⁺469.1.

Example 254N-((1R)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(33 mg) was resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=70/30, subsequently changed to 50/50) to give the titlecompound having a longer retention time (15 mg).

MS (API+): [M+H]⁺469.1.

Example 2557-methyl-2-oxo-N-(1-(5-(trifluoromethyl)pyridin-2-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from5-(trifluoromethyl)pyridine-2-carboxylic acid in the same manner as inStep A of Example 84, Steps C-F of Example 2 and Example Step L ofExample 72-I.

MS (API+): [M+H]⁺394.1.

Example 2567-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-amino-1-(4-(trifluoromethyl)phenyl)-2-methylpropan-2-ol hydrochloridein the same manner as in Steps K-M of Example 75.

MS (API+): [M+H]⁺ 449.2.

Example 257 Optically activeN-(3-methoxy-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(3-methoxy-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(300 mg) was resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=70/30, subsequently changed to 50/50) to give the titlecompound having a shorter retention time (140 mg).

MS (API+): [M+H]⁺439.1.

Example 258 Optically activeN-(3-methoxy-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(3-methoxy-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(300 mg) was resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=70/30, subsequently changed to 50/50) to give the titlecompound having a longer retention time (134 mg).

MS (API+): [M+H]⁺439.1.

Example 2596-methoxy-N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(3-methoxy-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(100 mg) was resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=70/30) to give the title compound having a shorterretention time (29.2 mg).

MS (API+): [M+H]⁺455.1.

Example 2606-methoxy-N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(3-methoxy-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(100 mg) was resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=70/30) to give the title compound having a longerretention time (33.8 mg).

MS (API+): [M+H]⁺455.1.

Example 261N-((1S)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-6-methoxy-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-6-methoxy-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(85 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=800/200) to give the title compound having a shorterretention time (29 mg).

MS (API+): [M+H]⁺469.2.

Example 262N-((1R)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-6-methoxy-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-6-methoxy-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(85 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=800/200) to give the title compound having a longerretention time (23 mg).

MS (API+): [M+H]⁺469.2.

Example 263N-((1S)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(270 mg) was resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=70/30, subsequently changed to 50/50), crystallized fromhexane/diisopropyl ether to give the title compound having a shorterretention time (116 mg).

MS (API+): [M+H]⁺439.1.

¹H NMR (300 MHz, DMSO-d₆) δ 0.95-1.03 (3H, m), 1.18 (3H, s), 2.27 (3H,s), 4.26-4.37 (1H, m), 4.38-4.47 (1H, m), 4.60-4.93 (2H, m), 7.13 (1H,d, J=1.5 Hz), 7.27 (2H, d, J=7.9 Hz), 7.42 (2H, d, J=9.0 Hz), 7.87 (1H,d, J=1.5 Hz), 10.54 (1H, d, J=8.3 Hz), 10.77 (1H, s).

Example 264N-((1R)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(85 mg) was resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=70/30, subsequently changed to 50/50), and crystallizedfrom hexane/diisopropyl ether to give the title compound having a longerretention time (103 mg).

MS (API+): [M+H]⁺439.1.

Example 265 Optically active7-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(478 mg) was resolved by HPLC (column: CHIRALPAK IA, 400 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=700/300), and recrystallized from hexane/ethyl acetate togive the title compound having a longer retention time (170 mg).

MS (API+): [M+H]⁺449.1.

Example 266 Optically active7-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-cyclopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(478 mg) was resolved by HPLC (column: CHIRALPAK IA, 400 mmID×250 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=700/300), and recrystallized from hexane/ethyl acetate togive the title compound having a shorter retention time (156 mg).

MS (API+): [M+H]⁺449.1.

Example 267N-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) methyl 2-bromo-2-(4-(trifluoromethyl)phenyl)acetate

The title compound was obtained from (4-(trifluoromethyl)phenyl)aceticacid in the same manner as in Steps A and Step D of Example 185.

¹H NMR (300 MHz, DMSO-d₆) δ 3.75 (3H, s), 5.98-6.21 (1H, m), 7.79 (4H,s).

B) methyl azido(4-(trifluoromethyl)phenyl)acetate

To a solution of methyl 2-bromo-2-(4-(trifluoromethyl)phenyl)acetate(11.8 g) in acetonitrile (265 mL) was added sodium azide (1.55 g) at 0°C. The reaction mixture was stirred at room temperature for 4 hr, andadded to water, and the mixture was extracted with ethyl acetate. Theextract was washed with saturated brine, and dried over anhydrous sodiumsulfate, and the solvent was evaporated under reduced pressure. Theresidue was purified by silica gel column chromatography (hexane/ethylacetate) to give the title compound (10.8 g).

¹H NMR (300 MHz, CDCl₃) δ 3.80 (3H, s), 5.08 (1H, s), 7.53 (2H, d, J=8.3Hz), 7.68 (2H, d, J=8.3 Hz).

C) methyl amino(4-(trifluoromethyl)phenyl)acetate

To a solution of methyl azido(4-(trifluoromethyl)phenyl)acetate (10.6 g)in methanol (408 mL) was added 10% palladium-carbon (containing 50%water, 1.10 g). The reaction mixture was stirred at room temperature for6 hr under hydrogen atmosphere, the catalyst was filtered off, and thefiltrate was concentrated under reduced pressure to give the titlecompound (9.13 g).

MS (API+): [M+H]⁺234.1.

D) methyl((tert-butoxycarbonyl)amino)(4-(trifluoromethyl)phenyl) acetate

The title compound was obtained from methyl2-amino-2-(4-(trifluoromethoxy)phenyl)acetate in the same manner as inStep G of Example 75.

MS (API−): [M−H]⁻332.1.

E)tert-butyl(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)carbamate

The title compound was obtained in the same manner as in Step B ofExample 250.

MS (API−): [M−H]⁻332.2.

F) 1-amino-2-methyl-1-(4-(trifluoromethyl)phenyl)propan-2-olhydrochloride

The title compound was obtained in the same manner as in Step B ofExample 92.

MS (API+), found: 234.1.

G)N-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from1-amino-2-methyl-1-(4-(trifluoromethyl)phenyl)propan-2-ol hydrochloridein the same manner as in Steps I-L of Example 66.

MS (API+): [M+H]⁺439.2.

Example 268 Optically activeN-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(221 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=50/50) to give the title compound having a shorterretention time (71.7 mg).

MS (API+): [M+H]⁺439.2.

Example 269 Optically activeN-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(221 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=50/50) to give the title compound having a longerretention time (78.3 mg).

MS (API+): [M+H]⁺439.2.

Example 270 Optically active7-methyl-2-oxo-N-(1-(5-(trifluoromethyl)pyridin-2-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-methyl-2-oxo-N-(1-(5-(trifluoromethyl)pyridin-2-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(296 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=450/550) to give the title compound having a shorterretention time (136 mg).

MS (API+): [M+H]⁺ 394.1.

Example 271 Optically active7-methyl-2-oxo-N-(1-(5-(trifluoromethyl)pyridin-2-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

Racemic7-methyl-2-oxo-N-(1-(5-(trifluoromethyl)pyridin-2-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(296 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=450/550) to give the title compound having a longerretention time (134 mg).

MS (API+): [M+H]⁺ 394.1.

Example 272N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide A) methyl2-((5-methyl-3-nitropyridin-2-yl)amino)acetate

To a mixture of methyl glycinate hydrochloride (8.32 g) and2-chloro-5-methyl-3-nitropyridine (7.62 g) in N,N-dimethylformamide (100mL) was added triethylamine (18.5 mL). The reaction mixture was stirredat 80° C. for 16 hr, and the solvent was evaporated under reducedpressure. To the residue was added water, and the mixture was extractedwith ethyl acetate. The extract was washed with water, and dried overanhydrous sodium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(ethyl acetate/hexane) to give the title compound (6.99 g).

¹H NMR (300 MHz, DMSO-d₆) δ 2.24 (3H, s), 3.64 (3H, s), 4.28 (2H, d,J=5.7 Hz), 8.27-8.37 (2H, m), 8.60 (1H, t, J=5.7 Hz).

B) 7-methyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of methyl 2-((5-methyl-3-nitropyridin-2-yl)amino)acetate(6.99 g) in ethanol (100 mL) was added 10% palladium-carbon (containing50% water, 2.00 g). The reaction mixture was stirred overnight at roomtemperature under hydrogen atmosphere, the catalyst was filtered off,and the filtrate was concentrated under reduced pressure. To the residuewas added ethanol (100 mL), the reaction mixture was heated at refluxfor 5 hr, and the solvent was evaporated to about ⅓ of volume underreduced pressure. To the residue was added diisopropyl ether, and theprecipitated solid was collected by filtration, washed with diisopropylether, and dried under reduced pressure to give the title compound (4.56g).

¹H NMR (300 MHz, DMSO-d₆) δ 2.09 (3H, s), 3.85 (2H, d, J=1.5 Hz), 6.45(1H, s), 6.72-6.80 (1H, m), 7.39-7.48 (1H, m), 10.31 (1H, s).

C) 4-nitrophenyl7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate

To a mixture of 7-methyl-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one (1.00g) in N,N-dimethylacetamide (40 mL) and pyridine (15 mL) was added4-nitrophenyl chloroformate (1.48 g) at room temperature. The reactionmixture was stirred at room temperature for 16 hr, and water was addedthereto. The precipitated solid was collected by filtration, washed withwater, and dried under reduced pressure to give the title compound (1.63g).

MS (API+): [M+H]⁺ 329.1.

D) 2-amino-2-(3-fluoro-4-(trifluoromethoxy)phenyl)acetonitrile

3-Fluoro-4-(trifluoromethoxy)benzaldehyde (10 g) was dissolved in 2 Mammonia/methanol solution (96 mL), titanium(IV) tetraisopropoxide (15.5mL) was added thereto under ice-cooling. The reaction mixture wasstirred at the same temperature for 15 min, trimethylsilanecarbonitrile(9.61 mL) was added thereto, and the mixture was stirred at roomtemperature for 20 hr. The solvent was evaporated under reducedpressure, and to the residue were added ethyl acetate and saturatedaqueous sodium hydrogen carbonate solution. The insoluble substance wasfiltered off using Celite, and the filtrate was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (ethyl acetate/hexane) to give the titlecompound (9.4 g).

¹H NMR (300 MHz, CDCl₃) δ 2.01 (2H, brs), 4.93 (1H, s), 7.29-7.53 (3H,m).

E) tert-butyl(cyano(3-fluoro-4-(trifluoromethoxy)phenyl)methyl)carbamate

To a solution of2-amino-2-(3-fluoro-4-(trifluoromethoxy)phenyl)acetonitrile (9.4 g) intetrahydrofuran (200 mL) was added di-tert-butyl dicarbonate (10.3 mL)and triethylamine (7.27 mL) at room temperature. The reaction mixturewas stirred at 40° C. for 20 hr, water was added thereto, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (ethyl acetate/hexane) to give thetitle compound (8.47 g).

MS (API+): [M+H]⁺ 335.1.

F)tert-butyl(2-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-oxoethyl)carbamate

To a mixture oftert-butyl(cyano(3-fluoro-4-(trifluoromethoxy)phenyl)methyl)carbamate(9.4 g), potassium carbonate (3.89 g) and dimethyl sulfoxide (200 mL)was added 35% aqueous hydrogen peroxide (4.66 mL) at room temperature.The reaction mixture was stirred at room temperature for 4 hr, water wasadded thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (ethyl acetate/hexane) to give the title compound (3.84g).

MS (API+), found: 253.0.

G) methyl2-((tert-butoxycarbonyl)amino)-2-(3-fluoro-4-(trifluoromethoxy)phenyl)acetate

To a solution oftert-butyl(2-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-oxoethyl)carbamate(3.84 g) in methanol (100 mL) was added 8 M aqueous sodium hydroxidesolution (2.8 mL) at room temperature. The reaction mixture was heatedat reflex overnight, and the methanol was evaporated under reducedpressure. The residue was neutralized with 1 M hydrochloric acid, andthe mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous magnesium sulfate, andthe solvent was evaporated under reduced pressure. To a mixture of theresidue (3.85 g) and potassium carbonate (1.81 g) inN,N-dimethylformamide (50 mL) was added methyl iodide (0.750 mL) at roomtemperature. The reaction mixture was stirred at room temperature for 2hr, water was added thereto, and the mixture was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (hexane/ethyl acetate) to give the titlecompound (1.90 g).

MS (API+), found: 268.0.

H)tert-butyl(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)carbamate

To a solution of methyl2-((tert-butoxycarbonyl)amino)-2-(3-fluoro-4-(trifluoromethoxy)phenyl)acetate(1.90 g) in tetrahydrofuran (60 mL) was slowly added 3 M methylmagnesiumbromide/diethyl ether solution (5.17 mL) at 0° C. The reaction mixturewas stirred at room temperature for 3 hr, 1 M hydrochloric acid at 0° C.was added thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (1.53g).

¹H NMR (300 MHz, CDCl₃) δ 1.06 (3H, s), 1.29-1.50 (13H, m), 4.38-4.52(1H, m), 5.47-5.60 (1H, m), 7.07-7.30 (3H, m).

I) 1-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methylpropan-2-olhydrochloride

Totert-butyl(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)carbamate(3.01 g) was added 4 M hydrogen chloride/ethyl acetate solution (30 mL).The reaction mixture was stirred at room temperature for 1 hr, and thesolvent was evaporated under reduced pressure. The residue was washedwith diisopropyl ether to give the title compound (2.22 g).

MS (API+), found: 268.1.

J)N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of 4-nitrophenyl7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (328mg) and1-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methylpropan-2-olhydrochloride (334 mg) in N,N-dimethylformamide (10 mL) was addedtriethylamine (0.335 mL) at room temperature. The reaction mixture wasstirred at room temperature for 16 hr, water was added thereto, and themixture was extracted with ethyl acetate. The extract was washedsuccessively with water and saturated brine, and dried over anhydrousmagnesium sulfate, and the solvent was evaporated under reducedpressure. The residue was purified by silica gel column chromatography(hexane/ethyl acetate), and recrystallized from hexane/ethyl acetate togive the title compound (357 mg).

MS (API+): [M+H]⁺ 457.1.

¹H NMR (300 MHz, CDCl₃) δ 1.16 (3H, s), 1.37 (3H, s), 1.62 (1H, s), 2.32(3H, s), 4.54-4.74 (2H, m), 4.85 (1H, d, J=8.3 Hz), 7.02 (1H, d, J=1.1Hz), 7.14-7.21 (1H, m), 7.21-7.30 (2H, m), 7.86-7.95 (1H, m), 8.78 (1H,s), 10.84 (1H, d, J=8.3 Hz).

Example 273 Optically activeN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(349 mg) was resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=90/10, subsequently changed to 70/30), and recrystallizedfrom acetone/heptane to give the title compound having a shorterretention time (140 mg).

MS (API+): [M+H]⁺ 457.1.

Example 274 Optically activeN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(349 mg) was resolved by HPLC (column: CHIRALPAK IA, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=90/10, subsequently changed to 70/30), and recrystallizedfrom acetone/heptane to give the title compound having a longerretention time (107 mg).

MS (API+): [M+H]⁺ 457.1.

Example 275N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) ethyl(5-bromopyridin-3-yl)carbamate

To a mixture of 5-bromopyridin-3-amine (35.4 g) and pyridine (19.8 mL)in tetrahydrofuran (600 mL) was slowly added ethyl chloroformate (23.4mL) at 0° C. The reaction mixture was stirred overnight at roomtemperature under nitrogen atmosphere, and poured into water, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. To the residue was addeddiisopropyl ether (400 mL), the mixture was stirred at room temperaturefor 20 min, and the obtained solid was collected by filtration to givethe title compound (29.0 g).

MS (API+):[M+H]⁺ 245.1.

B) ethyl(5-bromo-2-nitropyridin-3-yl)carbamate

To a solution of ethyl(5-bromopyridin-3-yl)carbamate (19.0 g) in conc.sulfuric acid (37.2 mL) was slowly added fuming nitric acid (26.1 mL) at0° C. The reaction mixture was stirred at room temperature for 72 hrunder nitrogen atmosphere. The reaction mixture was slowly poured intoice, the pH of the mixture was adjusted to 9 with 28% aqueous ammonia,and the mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous sodium sulfate, and thesolvent was evaporated under reduced pressure. To the residue was addedethyl acetate/hexane, the mixture was stirred for 15 min, and theresulting solid was collected by filtration, and washed with hexane togive the title compound (13.9 g).

MS (API+):[M+H]⁺ 290.1.

C) 5-methoxy-2-nitropyridin-3-amine

To a solution of ethyl(5-bromo-2-nitropyridin-3-yl)carbamate (31.1 g) inmethanol (900 mL) was added 28% sodium methoxide/methanol solution (83.0g) at room temperature. The reaction mixture was stirred at 65° C. for 4hr under nitrogen atmosphere, and the solvent was evaporated to about150 mL under reduced pressure. To the residue was added saturatedaqueous ammonium chloride solution, and the mixture was stirred at roomtemperature for 20 min, and the solvent was evaporated to about 100 mLunder reduced pressure. The resulting solid was collected by filtration,and washed with water to give the title compound (16.6 g).

MS (API+):[M+H]⁺ 170.2.

D) 2-chloro-N-(5-methoxy-2-nitropyridin-3-yl)acetamide

To a solution of 5-methoxy-2-nitropyridin-3-amine (24.7 g) inN,N-dimethylformamide (740 mL) was slowly added a solution ofchloroacetyl chloride (23.2 mL) in tetrahydrofuran (40 mL) at 0° C. Thereaction mixture was stirred at room temperature for 3 hr under nitrogenatmosphere, and the solvent was evaporated under reduced pressure. Tothe residue was added saturated aqueous sodium hydrogen carbonatesolution, and the mixture was extracted with ethyl acetate. The extractwas washed with saturated brine, and dried over anhydrous magnesiumsulfate, and the solvent was evaporated under reduced pressure. To theresidue was added diisopropyl ether/hexane, and the mixture was stirredat room temperature for 30 min. The obtained solid was collected byfiltration, and washed with diisopropyl ether/hexane to give the titlecompound (34.1 g).

MS (API+): [M+H]⁺ 246.0.

E) N-(2-amino-5-methoxypyridin-3-yl)-2-chloroacetamide

A mixture of 2-chloro-N-(5-methoxy-2-nitropyridin-3-yl)acetamide (34.1g), ammonium chloride (44.6 g), iron (27.1 g), ethanol (823 mL) andwater (206 mL) was stirred at 75° C. for 40 min, and the solvent wasevaporated under reduced pressure. To the residue were addedtetrahydrofuran (500 mL) and saturated aqueous sodium hydrogen carbonatesolution (300 mL), and the reaction mixture was stirred for 15 min. Theinsoluble substance was filtered off through Celite, to the filtrate wasadded saturated brine, and the mixture was extracted with ethyl acetate.The extract was washed with saturated brine, and the solvent wasevaporated under reduced pressure. To the residue was added diisopropylether/hexane, and the obtained solid was collected by filtration, andwashed with diisopropyl ether/hexane to give the title compound (26.3 g)

MS (API+):[M+H]⁺ 216.1.

F) benzyl(3-((chloroacetyl)amino)-5-methoxypyridin-2-yl)carbamate

To a mixture of N-(2-amino-5-methoxypyridin-3-yl)-2-chloroacetamide(2.74 g), pyridine (5.14 mL) and tetrahydrofuran (85 mL) was slowlyadded benzyl chloroformate (2.72 mL) at 0° C. The reaction mixture wasstirred at room temperature for 1 hr, and ethyl acetate was addedthereto. The mixture was washed with a mixture of saturated aqueoussodium hydrogen carbonate solution and saturated brine, and the solventwas evaporated under reduced pressure. The residue was purified bysilica gel column chromatography (hexane/ethyl acetate), and theobtained solid was washed with diisopropyl ether to give the titlecompound (3.79 g).

¹H NMR (300 MHz, DMSO-d₆) δ 3.82 (3H, s), 4.36 (2H, s), 5.13 (2H, s),7.30-7.43 (5H, m), 7.87 (1H, d, J=3.0 Hz), 7.95 (1H, d, J=2.6 Hz), 9.46(1H, s), 9.64 (1H, s).

G) benzyl7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate

To a solution ofbenzyl(3-((chloroacetyl)amino)-5-methoxypyridin-2-yl)carbamate (200 mg)in N,N-dimethylformamide (11 mL) was added cesium carbonate (279 mg) at50° C., and the reaction mixture was stirred at 50° C. for 30 min. Thereaction mixture was diluted with ethyl acetate, and the mixture waswashed with saturated brine, and the solvent was evaporated underreduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (115mg).

¹H NMR (300 MHz, DMSO-d₆) δ 3.81 (3H, s), 4.36 (2H, s), 5.20 (2H, s),6.92 (1H, d, J=2.6 Hz), 7.27-7.43 (5H, m), 7.84 (1H, d, J=2.6 Hz), 10.72(1H, s).

H) 7-methoxy-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one

To a solution of benzyl7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate(0.722 g) in tetrahydrofuran (46.1 mL) was added 10% palladium-carbon(containing 50% water, 0.049 g), and the reaction mixture was stirred atroom temperature for 15 hr under hydrogen atmosphere. To the reactionmixture was added methanol at 50° C. to dissolve the precipitated solid,the catalyst was filtered off, and the filtrate was concentrated underreduced pressure. The obtained solid was washed with diisopropyl etherto give the title compound (0.380 g).

MS (API+): [M+H]⁺180.2.

I) 2-amino-2-(3-fluoro-4-(trifluoromethoxy)phenyl)acetonitrile

3-Fluoro-4-(trifluoromethoxy)benzaldehyde (10 g) was dissolved in 2 Mammonia/methanol solution (96 mL), and titanium(IV) tetraisopropoxide(15.5 mL) was added thereto under ice-cooling. The reaction mixture wasstirred at the same temperature for 15 min, trimethylsilanecarbonitrile(9.61 mL) was added thereto, and the mixture was stirred at roomtemperature for 20 hr. The solvent was evaporated under reducedpressure, and to the residue were added ethyl acetate and saturatedaqueous sodium hydrogen carbonate solution. The insoluble substance wasfiltered off using Celite, and the filtrate was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (ethyl acetate/hexane) to give the titlecompound (9.4 g).

¹H NMR (300 MHz, CDCl₃) δ 2.01 (2H, brs), 4.93 (1H, s), 7.29-7.53 (3H,m).

J) tert-butyl(cyano(3-fluoro-4-(trifluoromethoxy)phenyl)methyl)carbamate

To a solution of2-amino-2-(3-fluoro-4-(trifluoromethoxy)phenyl)acetonitrile (9.4 g) intetrahydrofuran (200 mL) were added di-tert-butyl dicarbonate (10.3 mL)and triethylamine (7.27 mL) at room temperature. The reaction mixturewas stirred at 40° C. for 20 hr, water was added thereto, and themixture was extracted with ethyl acetate. The extract was washed withsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (ethyl acetate/hexane) to give thetitle compound (8.47 g).

MS (API+): [M+H]⁺ 335.1.

K)tert-butyl(2-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-oxoethyl)carbamate

To a mixture oftert-butyl(cyano(3-fluoro-4-(trifluoromethoxy)phenyl)methyl)carbamate(9.4 g), potassium carbonate (3.89 g) and dimethyl sulfoxide (200 mL)was added 35% aqueous hydrogen peroxide (4.66 mL) at room temperature.The reaction mixture was stirred at room temperature for 4 hr, water wasadded thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (ethyl acetate/hexane) to give the title compound (3.84g).

MS (API+), found: 253.0.

L) methyl2-((tert-butoxycarbonyl)amino)-2-(3-fluoro-4-(trifluoromethoxy)phenyl)acetate

To a solution oftert-butyl(2-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-oxoethyl)carbamate(3.84 g) in methanol (100 mL) was added 8 M aqueous sodium hydroxidesolution (2.8 mL) at room temperature. The reaction mixture was heatedat reflex overnight, and the methanol was evaporated under reducedpressure. The residue was neutralized with 1 M hydrochloric acid, andthe mixture was extracted with ethyl acetate. The extract was washedwith saturated brine, and dried over anhydrous magnesium sulfate, andthe solvent was evaporated under reduced pressure. To a mixture of theresidue (3.85 g) and potassium carbonate (1.81 g) inN,N-dimethylformamide (50 mL) was added methyl iodide (0.750 mL) at roomtemperature. The reaction mixture was stirred at room temperature for 2hr, water was added thereto, and the mixture was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was purified by silicagel column chromatography (hexane/ethyl acetate) to give the titlecompound (1.90 g).

MS (API+), found: 268.0.

M)tert-butyl(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)carbamate

To a solution of methyl2-((tert-butoxycarbonyl)amino)-2-(3-fluoro-4-(trifluoromethoxy)phenyl)acetate(1.90 g) in tetrahydrofuran (60 mL) was slowly added 3 M methylmagnesiumbromide/diethyl ether solution (5.17 mL) at 0° C. The reaction mixturewas stirred at room temperature for 3 hr, 1 M hydrochloric acid at 0° C.was added thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was purified by silica gel columnchromatography (hexane/ethyl acetate) to give the title compound (1.53g).

¹H NMR (300 MHz, CDCl₃) δ 1.06 (3H, s), 1.29-1.50 (13H, m), 4.38-4.52(1H, m), 5.47-5.60 (1H, m), 7.07-7.30 (3H, m).

N) 1-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methylpropan-2-olhydrochloride

Totert-butyl(l-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)carbamate(3.01 g) was added 4 M hydrogen chloride/ethyl acetate solution (30 mL).The reaction mixture was stirred at room temperature for 1 hr, and thesolvent was evaporated under reduced pressure. The residue was washedwith diisopropyl ether to give the title compound (2.22 g).

MS (API+), found: 268.1.

O)N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of 7-methoxy-3,4-dihydropyrido[2,3-b]pyrazin-2(1H)-one(233 mg) in tetrahydrofuran (15 mL) were added 4-nitrophenylchloroformate (315 mg) and N,N-diisopropylethylamine (0.341 mL) at roomtemperature. The reaction mixture was stirred at room temperature for 24hr, water was added thereto, and the mixture was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. To a solution of the residue inN,N-dimethylformamide (15 mL) were added1-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methylpropan-2-olhydrochloride (395 mg) and triethylamine (0.544 mL) at room temperature.The reaction mixture was stirred at room temperature for 20 hr, waterwas added thereto, and the mixture was extracted with ethyl acetate. Theextract was washed successively with water and saturated brine, anddried over anhydrous magnesium sulfate, and the solvent was evaporatedunder reduced pressure. The residue was crystallized from hexane/ethylacetate to give the title compound (492 mg).

MS (API+): [M+H]⁺473.1.

¹H NMR (300 MHz, CDCl₃) δ 1.15 (3H, s), 1.38 (3H, s), 1.61 (1H, s), 3.89(3H, s), 4.52-4.74 (2H, m), 4.84 (1H, d, J=8.3 Hz), 6.79 (1H, d, J=2.6Hz), 7.14-7.31 (3H, m), 7.75 (1H, d, J=2.6 Hz), 8.44-8.60 (1H, m), 10.49(1H, d, J=8.3 Hz).

Example 276 Optically activeN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(369 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=850/150), and recrystallized from acetone/heptane to givethe title compound having a shorter retention time (148 mg).

MS (API+): [M+H]⁺ 473.1.

¹H NMR (300 MHz, CDCl₃) δ 1.15 (3H, s), 1.37 (3H, s), 1.64 (1H, s), 3.89(3H, s), 4.53-4.72 (2H, m), 4.85 (1H, d, J=8.3 Hz), 6.81 (1H, d, J=2.6Hz), 7.13-7.31 (3H, m), 7.75 (1H, d, J=2.6 Hz), 8.90 (1H, brs), 10.50(1H, d, J=8.3 Hz).

Example 277 Optically activeN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

RacemicN-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide(369 mg) was resolved by HPLC (column: CHIRALPAK AD, 50 mmID×500 mmL,manufactured by Daicel Chemical Industries, Ltd., mobile phase:hexane/ethanol=850/150), and recrystallized from acetone/heptane to givethe title compound having a longer retention time (144 mg).

MS (API+): [M+H]⁺473.1.

¹H NMR (300 MHz, CDCl₃) δ 1.15 (3H, s), 1.37 (3H, s), 1.63 (1H, s), 3.89(3H, s), 4.52-4.74 (2H, m), 4.85 (1H, d, J=8.3 Hz), 6.81 (1H, d, J=2.6Hz), 7.11-7.31 (3H, m), 7.75 (1H, d, J=2.6 Hz), 8.78 (1H, brs), 10.50(1H, d, J=8.3 Hz).

Example 278N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-nitrophenyl7-methoxy-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylateand 1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethanaminehydrochloride in the same manner as in Step D of Example 19.

MS (API+): [M+H]⁺ 473.1.

Example 279N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-6-methoxy-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

The title compound was obtained from 4-nitrophenyl6-methoxy-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylateand 1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethanaminehydrochloride in the same manner as in Step D of Example 19.

MS (API+): [M+H]⁺ 473.1.

Example 280N-(2-cyano-1-(3-fluoro-4-(trifluoromethoxy)phenyl)ethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideA) 3-amino-3-(3-fluoro-4-(trifluoromethoxy)phenyl)propanoic acid

To a solution of 3-fluoro-4-(trifluoromethoxy)benzaldehyde (2.08 g) inethanol (40 mL) were added malonic acid (1.35 g) and ammonium acetate(1.16 g) at room temperature, and the mixture was stirred at 80° C. for20 hr. The reaction mixture was filtered, and the obtained solid waswashed with ethanol to give the title compound (1.48 g).

MS (API+): [M+H]⁺ 268.1.

B)tert-butyl(3-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-3-oxopropyl)carbamate

To a solution of3-amino-3-(3-fluoro-4-(trifluoromethoxy)phenyl)propanoic acid (1.48 g)in tetrahydrofuran (50 mL) were added di-tert-butyl dicarbonate (1.54mL) and 2 M aqueous sodium hydroxide solution (4.0 mL), and the mixturewas stirred at room temperature for 20 hr. The reaction mixture wasneutralized with 1 M hydrochloric acid, and the mixture was extractedwith ethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. A mixture of the residue,1H-benzotriazol-1-ol ammonium salt (1.01 g) and1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (1.27 g) inN,N-dimethylformamide (35 mL) was stirred at room temperature for 24 hr,water was added thereto, and the mixture was extracted with ethylacetate. The extract was washed successively with water and saturatedbrine, and dried over anhydrous magnesium sulfate, and the solvent wasevaporated under reduced pressure. The residue was crystallized fromhexane/ethyl acetate to give the title compound (1.38 g).

MS (API+): [M−H]⁻365.0.

C)tert-butyl(2-cyano-1-(3-fluoro-4-(trifluoromethoxy)phenyl)ethyl)carbamate

To a solution oftert-butyl(3-amino-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-3-oxopropyl)carbamate(1.0 g) in toluene/tetrahydrofuran (1:1, 75 mL) was added thionylchloride (0.498 mL) at room temperature. The reaction mixture wasstirred at 60° C. for 20 hr, and the solvent was evaporated underreduced pressure. To the residue was added water, and the mixture wasextracted with ethyl acetate. The extract was washed successively withwater and saturated brine, and dried over anhydrous magnesium sulfate,and the solvent was evaporated under reduced pressure. The residue waspurified by silica gel column chromatography (hexane/ethyl acetate) togive the title compound (380 mg).

MS (API+): [M+H]⁺ 349.1.

D) 3-amino-3-(3-fluoro-4-(trifluoromethoxy)phenyl)propanenitrilehydrochloride

A mixture oftert-butyl(2-cyano-1-(3-fluoro-4-(trifluoromethoxy)phenyl)ethyl)carbamate(431 mg) and 4 M hydrogen chloride/ethyl acetate (5 mL) was stirred atroom temperature for 30 min. The solvent was evaporated under reducedpressure, and the residue was washed with diisopropyl ether to give thetitle compound (328 mg).

MS (API+), found: 249.0.

E)N-(2-cyano-1-(3-fluoro-4-(trifluoromethoxy)phenyl)ethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

To a solution of 4-nitrophenyl7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxylate (275mg) and 3-amino-3-(3-fluoro-4-(trifluoromethoxy)phenyl)propanenitrilehydrochloride (296 mg) in N,N-dimethylformamide (10 mL) was addedtriethylamine (0.334 mL) at room temperature. The reaction mixture wasstirred at room temperature for 20 hr, and then at 60° C. for 24 hr. Tothe reaction mixture was added water, and the mixture was extracted withethyl acetate. The extract was washed successively with water andsaturated brine, and dried over anhydrous magnesium sulfate, and thesolvent was evaporated under reduced pressure. The residue was purifiedby silica gel column chromatography (hexane/ethyl acetate) to give thetitle compound (349 mg).

MS (API+): [M+H]⁺ 454.1.

The compounds of Examples according to the above-mentioned method or amethod analogous thereto are shown in the following tables. Mass in thetables means measured value.

TABLE 1-1 Example No. IUPAC Name Structure Mass (M+ 1) Mass (M − 1) 1N-(1-(4-methoxyphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

339.0 2 2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

395.2 3 N-(1-(4-methoxyphenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

355.1 4 7-methyl-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

409.2 5 optically active 7-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

409.1 6 optically active 7-methyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

409.1 7 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

411.1 8 optically active 2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

395.1 9 optically active 2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

395.1 10 8-methyl-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

409.1 11 6-methyl-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

409.1 12 N-(2-methyl-1-(4- (trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]- pyrazine-4(1H)-carboxamide

409.1

TABLE 1-2 13 N-(2-hydroxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

397.1 14 N-(2-hydroxy-2-methyl-1-(4- (trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]- pyrazine-4(1H)-carboxamide

425.0 15 N-(cyclopropyl(4- (trifluoromethoxy)phenyl)methyl)-2-oxo-2,3-dihydropyrido[2,3-b]- pyrazine-4(1H)- carboxamide

407.0 16 2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)butyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H- carboxamide

409.0 17 1-methyl-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

¹H NMR (300 MHz, CDCl₃) δ 0.97 (3H, t, J = 7.5 Hz) 1.83-1.93 (2H, m),3.36 (3H, s), 4.69 (2H, s), 4.91 (1H, q, J = 6.9 Hz), 7.09 (1H, dd, J =7.8, 5.1 Hz), 7.18 (2H, d, J = 8.4 Hz), 7.27-7.37 (3H, m), 8.02 (1H, d,J = 4.8 Hz), 10.31 (1H, d, J = 7.5 Hz). 18 N-(1-(4-(difluoromethoxy)phenyl)propyl)-2- oxo-2,3-dihydropyrido[2,3-b]-pyrazine-4(1H)-carboxamide

377.1 19 2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-7-(trifluoromethyl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

463.2 20 2-oxo-7-phenyl-N-(1-(4- (trifluoromethoxy)phenyl) propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

471.3 21 6-bromo-3-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)- carboxamide

471.9 22 3-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)- carboxamide

394.0 23 6-methyl-3-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-3,4-dihydropyrazino[2,3-b]pyrazine-1(2H)- carboxamide

410.2

TABLE 1-3 24 N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

411.2 25 N-((1S)-2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

411.1 26 7-iodo-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

521.1 27 2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-7-vinyl-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

421.1 28 N-(1-(biphenyl-4-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

387.2 29 7-ethyl-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

423.1 30 N-(1-(6-methoxypyridazin-3-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

343.2 31 N-(1-(3-fluoro-4- (trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]- pyrazine-4(1H)-carboxamide

413.1 32 N-(1-(2-methoxy-4- (trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]- pyrazine-4(1H)-carboxamide

425.1 33 N-(1-(4-hydroxyphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

327.1 34 N-(1-(2-fluoro-4- (trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]- pyrazine-4(1H)-carboxamide

413.2

TABLE 1-4 35 7-cyclopropyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

435.1 36 7-isopropyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

437.2 37 6-chloro-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

429.1 38 N-(1-(4-(1-methyl-1H-pyrazol-4- yl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

391.2 39 2-oxo-N-(1-(4-(prop-1-en-2- yl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

351.2 40 N-(1-(4-isopropylphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

353.2 41 N-(1-(4-(3,6-dihydro-2H-pyran-4- yl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

393.2 42 N-(2-amino-2-oxo-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

410.1 43 N-(cyano(4- (trifluoromethoxy)phenypmethyl)-2-oxo-2,3-dihydropyrido[2,3-b]- pyrazine-4(1H)-carboxamide

392.1 44 7-cyano-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

418.0 45 2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-6-(trifluoromethyl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

463.1 46 2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-6-vinyl-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

421.2

TABLE 1-5 47 6-benzyl-2-oxo-N-(1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

485.2 48 2-oxo-N-(1-(4-(tetrahydro-2H-pyran-4-yl)phenyl)propyl)-2,3-dihydropyrido-[2,3-b]pyrazine-4(1H)-carboxarnide

395.2 49 N-(1-(6-methoxypyridin-3-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

342.1 50 N-(1-(5-methoxypyrimidin-2- yl)propyl)-2-oxo-2,3-dihydropyrido-[2,3-b]pyrazine-4(1H)-carboxamide

343.2 51 6-ethyl-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

423.1 52 6-methoxy-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

425.1 53 N-(1-(4- (cyclopropylmethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

381.2 54 2-oxo-N-(1-(4- (trifluoromethyl)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

379.2 55 2-oxo-N-(pyridin-2-yl(4- (trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

444.2 56 N((3,5-dimethyl-1,2-oxazol-4- yl)(4-(trffluoromethoxy)phenyl)-methyl)-2-oxo-2,3-dihydropyrido- [2,3-b]pyrazine-4(1H)-carboxamide

462.1 57 N-((1-methyl-1H-pyrazol-4-yl)(4-(trtfluoromethoxy)phenyl)methyl)- 2-oxo-2,3-dihydropyrido[2,3-b]-pyrazine-4(1H)-carboxamide

447.2

TABLE 1-6 58 N-(2-(dimethylamino)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

424.1 59 N-(2-(methylsulfanyl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

427.1 60 N-(2-(methylsulfonyl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

459.2 61 N-(1-(5-methoxypyridin-2-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

342.1 62 6-cyano-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

418.2 63 7-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

441.2 64 7-methoxy-N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

441.2 65 7-methoxy-N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

441.2 66 N-(1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

459.1 67 N-((1S)-1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

459.1 68 N-((1R)-1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3 dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

459.1 69 7-methoxy-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo- 2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

425.1

TABLE 1-7 70 optically active 7-methoxy-N-(2-methoxy-1-(4-(trifluoromethyl)- phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

425.1 71 optically active 7-methoxy-N-(2-methoxy-1-(4-(trifluoromethyl)- phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

425.1 72 7-cyclopropyl-N-(2-hydroxy-2- methyl-1-(4-(trifluoromethoxy)-phenyl)propyl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

465.2 73 7-cyclopropyl-N-((1S)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)- phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

465.1 74 7-cyclopropyl-N-((1R)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)- phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

465.1 75 7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy- 2-methylpropyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

483.2 76 optically active 7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2- hydroxy-2-methylpropyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

483.2 77 optically active 7-cyclopropyl-N-(1-(3-fluoro-4-(trifluorornethoxy)phenyl)-2-hydroxy-2-methylpropyl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

483.2 78 2-oxo-N-(1-(4-(2,2,2- trifluoroethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

409.1 79 N-(2-(methylsulfinyl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

443.1 80 2-oxo-N-(1-(1-(2,2,2-trifluoroethyl)-1H-imidazol-4-yl)propyl)-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

383.1 81 2-oxo-N-(1-(1-(2,2,2-trjfluoroethyl)-1H-1,2,4-triazol-3-yl)propyl)-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

384.1

TABLE 1-8 82 N-(1-(4-isopropoxyphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

367.2 83 N-(1-(4-chlorophenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

345.1 84 2-oxo-N-(1-(2- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

395.1 85 N-(1-(4-methylphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

325.2 86 2-oxo-N-(1-(1-(2,2,2-trifluoroethyl)-1H-pyrazol-4-yl)propyl)-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

383.1 87 N-(1-(3-methyl-4- (trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]- pyrazine-4(1H)-carboxamide

409.1 88 N-(2-(dimethylamino)-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

438.1 89 N-(2-(methylamino)-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

424.1 90 N-(2-isopropoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

439.2 91 N-(2-(cyclopentyloxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

465.2 92 N-(3-amino-3-oxo-1-(4- (trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]- pyrazine-4(1H)-carboxamide

424.1 93 N-(3-(dimethylamino)-3-oxo- 1-(4-(trifluoromethoxy)phenyl)-propyl)-2-oxo-2,3-dihydropyrido- [2,3-b]-pyrazine-4(1H)-carboxamide

452.2

TABLE 1-9 94 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

425.2 95 3-methyl-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

409.1 96 N-(1-(4-(difluoromethyl)phenyl)-propyl)-2-oxo-2,3-dihydropyrido- [2,3-b]-pyrazine-4(1H)-carboxamide

361.2 97 N-(2-cyano-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

406.2 98 2-oxo-N-(1-(3- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

395.2 99 N-(1-(4-cyclopropylphenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

351.2 100 N-(3-methoxy-1-(4- (trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]- pyrazine-4(1H)-carboxamide

425.2 101 2-oxo-N-(2-(pyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

450.2 102 2-oxo-N-(2-(2-oxopyrrolidin-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

464.2 103 3-(((2-oxo-2,3-dihydropyrido[2,3-b]pyrazin-4(1H)-yl)carbonyl)amino)-3- (4-(trifluoromethoxy)phenyl)propylacetate

453.2 104 N-(3-hydroxy-1-(4- (trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]- pyrazine-4(1H)-carboxamide

410.8 105 N-(1-(4-(azetidin-1-yl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

364.2

TABLE 1-10 106 N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

425.2 107 N-((1S)-2-methoxy-1-(4- (trifluorormethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

425.1 108 N-(2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

447.1 109 N-(2-methoxy-1-(4- (trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

395.1 110 N-(2-methoxy-1-(4- (trifluoromethyl)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

409.2 111 N-(1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

429.1 112 N-(1-(3-fluoro-4- (trifIuoromethoxy)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

443.1 113 N-(1-(3-fluoro-4- (trrfluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

495.2 114 7-cyclopropyl-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

451.2 115 7-cyclopropyl-N-(2-methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

435.2 116 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

477.2 117 N-((1S)-1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

495.2

TABLE 1-11 118 N-((1R)-1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

495.1 119 7-cyclopropyl-N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

451.2 120 7-cyclopropyl-N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxanide

451.2 121 N-((1S)-1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)- carboxanide

429.1 122 N-((1R)-1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

429.1 123 N-((1S)-1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

443.1 124 N-((1R)-1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

443.1 125 7-cyclopropyl-N-(1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

469.2 126 optically active N-(2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

447.1 127 optically active N-(2-(difluoromethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

447.1 128 7-cyclopropyl-N-((1R)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2- methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

469.2 129 7-cyclopropyl-N-((1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2- methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

469.2

TABLE 1-12 130 N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(1H-pyrazol-1-yl)-2,3-dihydropyrido(2,3- b]pyrazine-4(1H)-carboxamide

477.2 131 N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(1H-pyrazol-yl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

477.2 132 N-(1-(4-bromophenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

419.1 133 N-(2-(2-methoxyethoxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

469.2 134 N-(2-methoxy-1-(4-(1H-pyrazol-1-yl)phenyl)ethyl)-7-methyl-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

407.2 135 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-7-(1-methyl-1H-pyrazol-3-yl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

491.2 136 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-7-(1-methyl-1H-pyrazol-4-yl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

491.2 137 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-7-(1-methyl-1H-pyrazol-5-yl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

491.2 138 7-isopropoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

469.1 139 7-(difluoromethoxy)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

477.2 140 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-6-oxo-6,7-dihydropteridine-8(5H)-carboxamide

412.2 141 7-ethoxy-N-(2-methoxy-1-(4-(trifluororrethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

455.2

TABLE 1-13 142 7-methyl-N-(oxetan-3-yl(4-(trifluoromethoxy)phenyl)methyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

437.1 143 N-(1-(3-fluoro-4-(1H-pyrazol-1-yl)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

425.2 144 N-(2-methoxy-1-(5-(1H-pyrazol-1-yl)pyridin-2-yl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

408.2 145 N-((1R)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

425.2 146 N-((1S)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

425.2 147 7-methyl-2-oxo-N-(1-(4-(1H-pyrrol-1-yl)phenyl)propyl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

390.2 148 7-methyl-2-oxo-N-(1-(4-(pyrrolidin-1-yl)phenyl)propyl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

394.3 149 7-(2-hydroxypropan-2-yl)-N-(2- methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

469.2 150 7-(azetidin-1-yl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

466.2 151 N-(1-(imidazo[1,2-a]pyridin-7-yl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

365.2 152 7-methyl-2-oxo-N-(1-(4- (trifluoromethoxy)phenyl)cyclopropyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

407.1 153 7-fluoro-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

429.1

TABLE 1-14 154 N-(2-methoxy-1-(4-(1H-pyrrol-1-yl)phenyl)ethyl)-7-methyl-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

406.2 155 7-chloro-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

445.1 156 N-(2-methoxy-1-(4-(pyrrolidin-1-yl)phenyl)ethyl)-7-methyl-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

410.3 157 N-(2-methoxy-1-(4-(1H-pyrrol-1- yl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

392.2 158 N-(2-methoxy-1-(4-(pyrrolidin-1- yl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

396.2 159 N-(1-(2,2-difluoro-1,3-benzodioxol-5-yl)propyl)-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

391.1 160 7-methyl-2-oxo-N-(2-(1H-pyrazol-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

461.2 161 optically active 7-methyl-2-oxo-N-(1-(4-(1H-pyrrol-1-yl)phenyl)propyl)-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

390.2 162 7-methyl-2-oxo-N-(1-(5-(1H-pyrazol-1-yl)-2-thienyl)propyl)-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

397.0 163 optically active 7-methyl-2-oxo-N-(1-(4-(1H-pyrrol-1-yl)phenyl)propyl)-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

390.2 164 7-methyl-2-oxo-N-(2-(1H-1,2,4-triazol-1-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

462.2 165 7-methyl-2-oxo-N-(1-(pyrazolo[1,5- a]pyridin-5-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

365.2

TABLE 1-15 166 7-methyl-N-(2-(oxetan-3-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

451.2 167 7-(difluoromethyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

461.1 168 7-methyl-2-oxo-N-(tetrahydro-2H-pyran-4-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

465.2 169 N-(2-(4-hydroxytetrahydro-2H-pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

495.1 170 7-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

451.2 171 N-(2-hydroxy-1-(4- (trifluoromethoxy)phenyl)pentyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

453.2 172 N-(3-((tert-butyl(dipheny))silyl)oxy)-2,2- dimethyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

691.4 173 N-(2-(1,3-dioxo-1,3-dihydro-2H-isoindol- 2-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

526.2 174 N-(2-cyclopropyl-2-oxo-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

435.1 175 N-(2-cyclopropyl-2-hydroxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

437.2 176 7-methyl-2-oxo-N-(2-(tetrahydro-2H- pyran-4-yl)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

479.2 177 2-oxo-N-(2-oxo-1-(4- (trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

409.1

TABLE 1-16 178 8-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

441.2 179 N-(2-hydroxy-1-(4- (trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

411.1 180 2-oxo-N-(2,2,2-trifluoro-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

435.1 181 7-methyl-2-oxo-N-(2-(pyridin-3-yloxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

488.2 182 N-(2-hydroxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

411.1 183 N-(1-(3,5-difluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

461.1 184 N-(3-hydroxy-2,2-dimethyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

453.2 185 N-(2-fluoro-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

427.1 186 2-oxo-N-(1-(4-(2H-1,2,3-triazol-2-yl)phenyl)propyl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

378.2 187 N-(2-fluoro-2-methyl-1-(4- (trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

441.2 188 N-(1-(3-fluoro-4-(pyrrolidin-1-yl)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

428.2 189 N-(1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

424.2

TABLE 1-17 190 8-(2-hydroxypropan-2-yl)-N-(2- methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

469.2 191 8-acetyl-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

453.1 192 8-(hydroxymethyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

441.2 193 N-(2-ethyl-2-hydroxy-1-(4-(trifluoromethoxy)phenyl)butyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

453.2 194 N-(2-amino-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

396.1 195 N-((4-bromo-2-fluorophenyl)(4-(trifluoromethoxy)phenyl)methyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

553.1 196 N-((4-bromo-2-hydroxyphenyl)(4-(trifluoromethoxy)phenyl)methyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

551.1 197 N-(2-((5-bromopyridin-3-yl)oxy)-1-(4-(trifluoromethoxy)phenyl)ethyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

566.1 198 N-((2-fluorophenyl)(4- (trifluoromethoxy)phenyl)methyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

475.2 199 N-((2-hydroxyphenyl)(4- (trifluoromethoxy)phenyl)methyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

473.2 200 7-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

451.2 201 7-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

451.2

TABLE 1-18 202 7-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

451.2 203 7-methyl-2-oxo-N-(tetrahydrofuran-2-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

451.2 204 7-methoxy-2-oxo-N-(1-(4-(pyrrolidin-1-yl)phenyl)propyl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

408.2 205 N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7- methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

455.3 206 7-methyl-2-oxo-N-(tetrahydrofuran-3-yl(4-(trifluoromethoxy)phenyl)methyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

451.2 207 N-((1S)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7- methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

455.2 208 N-((1R)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido-[2,3- b]pyrazine-4(1H)-carboxamide

455.1 209 7-cyclopropyl-N-(1-(3-fluoro-4- (trifluoromethyl)phenyl)-2-methoxyethyl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

453.1 210 7-methyl-2-oxo-N-(3,3,3-trifluoro-2- hydroxy-1-(4-(trifluoromethoxy)phenyl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

479.1 211 N-(1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

440.2 212 6-(4-methoxyphenyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

517.1 213 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(pyridin-3-yl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

488.1

TABLE 1-19 214 N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-6- phenyl-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

487.1 215 6-(2-methoxyphenyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

517.1 216 6-(3-methoxyphenyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

517.2 217 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(pyridin-4-yl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

488.1 218 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(2-thienyl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

493.1 219 6-(3-furyl)-N-(2-methoxy-1-(4-(trifluromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

477.1 220 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(3-thienyl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

493.1 221 N-(2-melhoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-6-(1-methyl-1H-pyrazol-5-yl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

491.1 222 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-6-(1-methyl-1H-pyrazol-3-yl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

491.1 223 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-6-(1-methyl)-1H-pyrazol-4-yl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

491.1 224 6-(3,5-dimethyl-1,2-oxazol-4-yl)-N-(2- methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

506.1 225 N-(1-(3-fluoro-4- (trifluoromethyl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

443.1

TABLE 1-20 226 optically active 7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2- methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

453.1 227 optically active 7-cyclopropyl-N-(1-(3-fluoro-4-(trifluoromethyl)phenyl)-2- methoxyethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

453.1 228 N-(2-methoxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

453.2 229 optically active N-(1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

440.2 230 optically active N(1-(3-fluoro-4-(1H-pyrrol-1-yl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

440.2 231 optically active 7-cyclopropyl-N-(2- methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

435.1 232 optically active N-(1-(3-fluoro-4- (trifluoromethyl)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

443.1 233 optically active 7-cyclopropyl-N-(2- methoxy-1-(4-(trifluoromethyl)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

435.1 234 optically active N-(1-(3-(fluoro-4-(trifluoromethyl)phenyl)-2- methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyazine-4(1H)- carboxamide

443.1 235 6-(3,6-dihydro-2H-pyran-4-yl)-N-(2- methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

493.1 236 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-6-(1-methyl-1,2,3,6-tetrahydropyridin-4-yl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

506.1 237 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(1,2,3,6-tetrahydropyridin-4-yl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

492.1

TABLE 1-21 238 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-6-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

425.0 239 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(pyridin-2-yl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

488.1 240 6-(2-furyl)-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

477.1 241 6-cyclopropyl-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

451.1 242 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(tetrahydro-2H-pyran-4-yl)-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

495.1 243 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-6-(1-methylpiperidin-4-yl)-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

508.1 244 N-(2-methoxy-1-(4- (trifluoromethoxy)phenyl)ethyl)-2-oxo-6-(piperidin-4-yl)-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

494.1 245 6-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

455.1 246 7-methoxy-N-(2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

455.1 247 N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7- methoxy-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

469.1 248 N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-6- methoxy-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

469.1 249 N-(3-methoxy-1-(4- (trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

439.1

TABLE 1-22 250 N-(2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

439.1 251 7-methoxy-N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-6- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

455.1 252 7-methoxy-N-((1R)-2-methoxy-1-(4-(trifluoromethoxy(phenyl)ethyl)-6- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

455.1 253 N-((1S)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7- methoxy-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

469.1 254 N-((1R)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7- methoxy-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

469.1 255 7-methyl-2-oxo-N-(1-(5-(trifluoromethyl)pyridin-2-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

394.1 256 7-cyctopropyl-N-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

449.2 257 opticallly active N-(3-methoxy-1-(4-(trifluoromethoxy)phenyl)propyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

439.1 258 N-(3-methoxy-1-(4- (trifluoromethoxy)phenyl)propyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

439.1 259 6-methoxy-N-((1S)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

455.1 260 6-methoxy-N-((1R)-2-methoxy-1-(4-(trifluoromethoxy)phenyl)ethyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

455.1 261 N-((1S)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-6- methoxy-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

469.2

TABLE 1-23 262 N-((1R)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-6- methoxy-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

469.2 263 N-((1S)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

439.1 264 N-((1R)-2-hydroxy-2-methyl-1-(4-(trifluoromethoxy)phenyl)propyl)-7- methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

439.1 265 optically active 7-cyclopropyl-N-(2- hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

449.1 266 optically active 7-cyclopropyl-N-2- hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propy)-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

449.1 267 N-(2-hydroxy-2-methyl-1-(4- (trifluoromethyl)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

439.2 268 optically active N-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

439.2 269 optically active N-(2-hydroxy-2-methyl-1-(4-(trifluoromethyl)phenyl)propyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

439.2 270 optically active 7-methyl-2-oxo-N-(1-(5-(trifluoromethyl)pyridin-2-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

394.1 271 optically active 7-methyl-2-oxo-N-(1-(5-(trifluoromethyl)pyridin-2-yl)propyl)-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

394.1 272 N-(1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methyl-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

457.1 273 optically active N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2- methylpropyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

457.1

TABLE 1-24 274 optically active N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2- methylpropyl)-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)- carboxamide

457.1 275 N-(1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methoxy-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

473.1 276 optically active N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methoxy-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

473.1 277 optically active N-(1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-hydroxy-2-methylpropyl)-7-methoxy-2-oxo-2,3- dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamide

473.1 278 N-(1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-6-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

473.1 279 N-(1-(3-fluoro-4- (trifluoromethoxy)phenyl)-2-methoxyethyl)-6-methoxy-7-methyl-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine- 4(1H)-carboxamide

473.1 280 N-(2-cyano-1-(3-fluoro-4- (trifluoromethoxy)phenyl)ethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3- b]pyrazine-4(1H)-carboxamide

454.1

Experimental Example 1

PDE Enzyme Inhibition Assay

Human PDE2A3 enzyme was generated from Sf9 cells transfected with thefull-length gene. The extracted enzyme from Sf9 cells was purified byHis-tag affinity column and gel filtration. The enzyme was stored at−70° C. until use. PDE activity was measured using a SPA (ScintillationProximity Assay) (GE Healthcare). To evaluate the inhibitory activity,10 μl of serial diluted compounds were incubated with 20 μl of PDEenzyme in assay buffer (50 mM HEPES-NaOH, 8.3 mM MgCl₂, 1.7 mM EGTA,0.1% BSA (pH 7.4)) for 30 min. at room temperature. Final concentrationof DMSO in the assay was 1 percent as compounds were tested in duplicatein 96-well half-area plates (Corning) or 384-well OptiPlate(PerkinElmer). To start the reaction, 10 μl of substrate [³H] cGMP (77nM, PerkinElmer) was added for a final assay volume of 40 μl. After 60min incubation at room temperature, 20 μl of 20 mg/ml yttrium SPA beadscontaining Zinc sulphate was added to terminate the PDE reaction. Afterbeing settled for further 1 hour, the assay plates were counted in ascintillation counter (PerkinElmer) to allow calculation of inhibitionrate. Inhibition rate was calculated on the basis of 0% control wellswith enzyme and DMSO, and 100% control wells without enzyme. The resultsare shown in Table 2.

TABLE 2 Example No. Inhibition Rate (%) (1 μM) 5 95 9 96 14 99 15 94 2599 31 96 35 95 52 93 54 95 60 97 64 99 66 101 67 101 70 98 73 99 76 10093 96 107 99 117 99 120 99 121 99 123 98 129 99 130 99 134 97 136 99 14398 146 98 152 97 160 99 162 97 167 99 200 100 207 98 222 99 226 100 22999 231 100 232 100 251 100 253 100 257 99 259 99 261 100 263 100 266 100268 99 273 98 276 101

Experimental Example 2

The improvement effect on MK-801((5S,10R)-5-methyl-10,11-dihydro-5H-5,10-epiminodibenzo[a,d][7]annulene)-induceddisorder in contextual fear conditioning test.

Experimental Animals

Male C57BL/6 mice were purchased from CLEA Japan, Inc. They were usedfor an experiment after a habituation period of at least one week aftercarrying them in the animal experimental facility. They were bred in theanimal experimental facility with environment in which 12-hourslight-dark cycle was performed, humidity and temperature werecontrolled, and free water drinking and feeding were allowed. Handlingof experimental animals and experimental procedure of this study wereapproved by the Experimental Animal Ethics Committee of TakedaPharmaceutical Company Limited.

Used Drugs

A test compound was suspended in 0.5% methylcellulose solution, andorally administered. MK-801 (maleate) (Sigma-Aldrich, St Louis, Mo.) wasdissolved in saline, and subcutaneously administered. All drugs wereadministered to mice at a dose of 10 mL/kg.

The improvement effect on MK-801-induced disorder in contextual fearconditioning test.

Contextual fear conditioning test is widely used as memory and learningtest system depending on the hippocampus and amygdala. The improvementeffect of test compounds on MK-801-induced disorder was investigated bycontextual fear conditioning test. Administrations of 0.5%methylcellulose and saline to the control groups were carried out 60minutes and 30 minutes before tests, respectively. Administrations of0.5% methylcellulose and MK-801 (maleate) to the vehicle groups werecarried out 60 minutes and 30 minutes before tests, respectively. Testcompounds and MK-801 (maleate) were administered 60 minutes and 30minutes before tests. In experiments, a chamber with a floor grid forelectric shock and a freezing measuring device (O'Hara & Co., Ltd.) wereused. The chamber was put in a soundproof box to block the noise fromoutside, and tests were performed. In the training session on day 1 ofthe experiment, after habituation for 3 minutes in the chamber, twoelectric footshocks were given to mice at 1-minute interval. In the testsession on day 2 of the experiment, mice were placed in the same chamberfor 7 minutes, and freezing was measured during that period. Thefreezing was calculated as a percentage of freezing rates duringmeasuring period with use of an automatic analysis software manufacturedby the O'Hara & Co., Ltd. All data were shown as the mean+standard error(n=10-11). A comparison between two groups was tested by Student'st-test (*p≦0.05, comparison with control group. ^(#)p≦0.05, comparisonwith group treated with MK-801 alone.).

The compounds in FIG. 1 correspond to the following compounds.

-   Compound A: Example 67-II-   Compound B: Example 73-   Compound C: Example 76-   Compound D: Example 263-   Compound E: Example 273-   Compound F: Example 64

The improvement effect on MK-801-induced deficits was shown by orallyadministering each of test compounds (A-F) to mice 60 minutes before thetests.

Formulation Example 1

(1) Compound of the Example 1 10.0 g (2) Lactose 70.0 g (3) Cornstarch50.0 g (4) Soluble starch  7.0 g (5) Magnesium stearate  3.0 g

After 10.0 g of the compound in Embodiment 1 and 3.0 g of magnesiumstearate are granulated in 70 ml aqueous solution of soluble starch (7.0g as soluble starch) and then dried, and the resulting mixture is mixedwith 70.0 g of lactose and 50.0 g of cornstarch (lactose, cornstarch,soluble starch and magnesium stearate are all products in compliancewith Japanese Pharmacopoeia 14^(th) Edition). The mixture is compressedto obtain a tablet.

INDUSTRIAL APPLICABILITY

According to the present invention, the compound having a PDE2Aselective inhibitory action, which is useful as an agent for theprophylaxis or treatment of schizophrenia, Alzheimer's disease and thelike, can be provided.

This application is based on patent application Nos. 100374/2012 and283470/2012 filed in Japan, the contents of which are herebyincorporated by reference.

The invention claimed is:
 1. A compound which is:N-((1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideor a salt thereof.
 2. A pharmaceutical composition comprising aneffective amount ofN-((1S)-1-(3-fluoro-4-(trifluoromethoxy)phenyl)-2-methoxyethyl)-7-methoxy-2-oxo-2,3-dihydropyrido[2,3-b]pyrazine-4(1H)-carboxamideor a salt thereof, and a pharmaceutically acceptable carrier.